Hanging wallpaper is a skill that looks more difficult that it really is. You can master the basics with common sense, the right tools, and some practice. As with any craft, beginners may make mistakes, but if you choose the right kind of paper and pattern for your first project, slip-ups can be remedied -- or avoided altogether.

Master paperhanger Scott McDonald, of Vertical View Paperhanging in New York City, suggests that you avoid costly hand-printed papers, which stain at the touch of one drop of water, rip easily, and permanently retain the slightest crease. Instead, simplify your project by selecting one of the many inexpensive vinyl-coated papers. They're washable, so excess glue can be wiped away with a damp sponge, and they stretch, to help align seams or to let you peel off and rehang a strip that isn't quite right. 

When choosing a design, look for a stripe or a dense, overall pattern, which will minimize tricky matching; steer clear of "drop repeat" patterns until you've mastered basic hanging techniques. Some paper comes with a blank selvage on each edge of the decorative panel to protect the printed area of the roll from damage during shipping. Avoid the tedious job of cutting off the selvages by requesting a pretrimmed paper. 

Prepare walls by spackling and sanding as you would for paint; imperfections will mar the final surface. Then apply a coat of primer (McDonald recommends oil-based primer). Once the primer has cured, the room is ready to be lined with a finish that will be a reward for all the effort you put into it.

Except for a few specialized items such as a seam roller and a plastic smoother, the basics include many items already in your toolbox or workroom.

1. Roller (9-inch)
2. Natural sponge
3. Angled paintbrush (1 1/2-inch)
4. Seam roller
5. Glue syringe
6. Straightedge
7. Single-edge blades
8. Utility knife
9. Pencil
10. Level
11. Tape measure
12. Scissors
13. Narrow scraper (3-inch)
14. Plastic smoother (8-inch)
15. Wide scraper (10-inch)
16. Terry-cloth rags

Wallpaper comes in various widths and lengths. The numbers in our chart are based on an American "double" roll, which typically covers about 66 square feet. To calculate how many rolls you need per room, divide the total square footage of the walls (including windows and doors) by the square footage of one roll. Buy at least 10 percent more paper to accommodate errors and adjustments, such as a 4-inch allowance for each strip. 

For patterns with a difficult-to-match drop repeat, you should prepare to buy substantially more paper to compensate for waste. (Ask your dealer's advice.) Save leftovers for future repairs.

Don't expect to achieve a perfect pattern match in a room when hanging the last strip beside the first one. To downplay the mismatch, hang the first strip in an inconspicuous corner, and then work around the room, back to that starting point (light arrows). 

Or, begin by centering the pattern at a focal point, and proceed in opposite directions, making sure the last two strips meet in an inconspicuous corner (dark arrows).

First, cut all strips of paper to size, leaving a 4-inch overhang on each end and making sure the pattern will align from strip to strip. A premixed "clear hang" glue is usually best, although other adhesives may work better with certain papers (ask your wallpaper dealer). 

Pour glue into a paint-roller tray: A roller applies glue more quickly and evenly than a brush, except on narrow strips or in corners, where an angle brush is helpful. 

Lay the first strip on a clean worktable, pattern-side down, so that any excess hangs over one end of the table. Make a pencil mark at the midpoint of the strip, and roll a thin layer of glue over half the strip. Let the glue cure, following package instructions.

Strips are easier to manage if you "book," or fold, them. Book by lifting the bottom edge of the glued half to the midpoint of the strip.

Tamp this edge down so the paper sticks to itself, but don't crease the fold. The pattern will now be facing up. Wipe off excess glue with a damp sponge (unless the paper is printed with water-soluble ink). Glue and book the other half of the strip. You then have about 15 minutes before the glue begins to dry, enough time to hang the strip.

Before papering, use a straightedge, a level, and a pencil to mark top to bottom where each strip will fit on the walls.

Carry the first glued and booked strip to the wall, and unfold the upper half of the strip. Align one of the edges of the strip with the appropriate pencil line, and place the top edge so that it slightly overlaps the ceiling or, as here, the base of the crown molding. Smooth the paper against the wall with your hands, moving sideways and downward until you reach the midpoint. Unfold, and affix the bottom half.

Paper strips hung precisely edge to edge produce the neatest seam. Place the new strip as close as possible to an affixed strip. With your hands flat on the new strip, push it gently up or down to align the pattern, keeping fingertips away from the edge to avoid tearing. Push the new strip toward the old one until the edges of both strips touch and just begin to buckle. Then, go over the seam with a smoother. After 10 to 15 minutes' drying time, run a paper roller along the seam in short up-and-down strokes.

In some spots, strips cannot hang exactly parallel -- in a corner, for instance, where walls are uneven. Positioning one strip to overlap another by 1/16 inch lets you cheat the alignment. Because an overlap creates a ridge, avoid using this seam in a prominent place. For thicker, fabric-covered papers, run a single-edge blade through both layers of the overlap, and peel away the underlying layers.

When choosing a wallpaper, remember that some patterns are harder to match. People tend to focus on the center of a wall, the interval between windows, and anything at eye level, so pay special attention to matching patterns at these points.

So long as you are able to hang full-width strips of paper, these are the easiest patterns to match. However, trimming to cover tight spaces can get tricky, since they break the pattern's rhythm.

This is the easiest type of nonstriped pattern for the novice to manage: The eye generally overlooks mismatches within a dense, small-figured design.

Designs like this latticework are simple to match, since the repeat begins and ends precisely within the width of each roll of paper.

Because the repeated motif extends beyond the width of the wallpaper roll, this sort of pattern is the most difficult to align at a seam -- and the likeliest to produce a lot of waste.

Many beginners are tempted to run a strip of paper to the end of the wall, crease it, continue past the corner onto the next wall, and then hang the next strip alongside it. But paper hung around a corner doesn't stick well and usually begins to pull away from the wall before long. For a neater, durable fit, follow this procedure:

Cut the strip so that only 1/2 inch extends beyond the corner. Glue and hang the strip, then trim it again with a single-edge blade, leaving just 1/8 inch of paper beyond the corner.

Align the next strip to overlap this 1/8-inch extension.

Hang the strip that meets one side of a window or door frame so that it overlaps the frame by 2 to 3 inches. Make horizontal cuts at the top and (for a window only) bottom of the frame. Press the paper above the frame flat against the wall. Trim the 2- to 3-inch excess beside the frame with a utility knife, and smooth it down. Smooth the paper below a windowsill, cutting in around any decorative molding. 

Paper the areas above and below the window or door frame, if necessary, then repeat the previous steps to hang and trim paper on the remaining side of the frame.

Paper retains a "memory" of being curled long after it has been unrolled. This can make it difficult to cut, glue, and hang. To avoid this problem, as soon as you unroll the paper, briefly reroll it in the opposite direction to counteract the original curl. The paper will then lie flat as you work.

Using a single-edge blade, cut along a straightedge in one slow, continuous motion down the length of the selvage; if you lift the blade in mid-cut, you may leave an irregular edge that will show up as a flaw on the wall. 

To halve the length of the edge you have to cut, trim after the paper has been glued and booked. (The exception is hand-printed paper, which often has uneven edges that are difficult to align. Such paper must always be cut before gluing.)

Sometimes wallpaper fails to adhere in an isolated spot, producing a bubble that mars the surface. Before removing a bubble, wait until the glue under the surrounding paper has dried. Use a glue syringe (available at paint stores) to pierce the bubble, and inject a few drops of wallpaper glue. Then, gently flatten this area with a plastic smoother.

Once you've papered a few simple walls, more complicated jobs are less daunting. Why not embellish that blank dining-room ceiling with a pattern that comes alive by candlelight? How about lining the guest room dormer with the same floral paper that covers the rest of the room, to make the angled window alcove feel cozier, or papering inside an archway to give it a sense of depth? 

Here, we will demonstrate time-tested strategies for some of the paperhanger's trickier moves. 

When tackling a stairwell, for instance, first paint the moldings and other woodwork. Then, paper the ceiling, running strips edge to edge across the ceiling's shortest dimension -- the shorter the strip, the easier it is to handle. If there is no cove molding, cut the ceiling paper to extend 1/8 inch onto the adjoining wall. The strips you glue to the wall will cover this overlap, resulting in a neat seam. As with any wallpaper project, the true trade secret is patience -- and a sponge to wipe up excess glue.

Most staircases have awkward angles that impede precise measurement. Wallpapers with thin, evenly spaced stripes or a small floral or geometric design are easiest to align. It doesn't matter if you start upstairs or down, but it's essential to measure the wall height on the longer side of each paper strip before cutting it, because the slope of the baseboard makes the wall progressively taller as the stairway descends.

Position ceiling strips to run the shortest distance from wall to wall -- the less paper you have to hold overhead, the better. Plan strips so the pattern is centered on the ceiling. Once you have cut the strips, apply a slightly heavier coat of glue than you would use for a wall, so that the paper dries more slowly. "Book" each glued strip by folding it in on itself. Standing on a stepladder or stool, push the paper onto the ceiling, and unbook it.

At cove moldings and other edges, use a plastic smoother to push the paper into place as squarely as possible; trim it with a utility knife only after the whole strip is in place. Keep a glue pot and a small brush handy for touching up paper edges that dry too quickly and come loose.

As soon as you glue strips of paper onto a stairway wall, affix and trim the bottom of each strip where it overlaps the molding of the diagonal baseboard that follows the stairs. Wherever the slope of the baseboard shifts, use a utility knife to make a straight cut from the top of the joint down, so the paper lies flat against the wall. Then press the paper firmly into place along the molding with a plastic smoother.

Finally, take a wide scraper blade or spackling knife, and press it tightly against the paper where it meets the edge of the baseboard molding. Using the scraper or spackling knife as a straightedge, cut the paper cleanly with the utility knife. Change the cutting blade often; if it isn't sharp, the paper will bunch up, snag, or tear.

Cut a strip of paper to lie flat against one of the low walls adjoining the dormer, and overlap the roof slope. Apply glue to the strip, and lightly tap the lower portion into place.

Cut a vertical slit all the way up the strip from the point where the low wall, the diagonal roofline, and the inside dormer wall intersect. Leave excess paper on the dormer wall. Starting 1/8 inch above the bottom of the slit, cut horizontally toward the left; discard the excess. 

Pat the lower portion of the strip in place, including the 1/8-inch overlap onto the roof slope. 

Position the upper right-hand portion of the strip on the dormer wall. Trim it to leave a 1/8-inch overlap onto the adjoining low wall.

Cut a new strip, and apply it to the sloped surface, matching the pattern at the seam with the low wall.

Paper the rest of the dormer wall. Repeat the above steps for the surfaces at the right-hand side of the dormer. Paper around the window frame as you would around any window.

As a finishing touch, many people like to paper the covers on electrical outlets and switches. Since paper is easily soiled by fingerprints, consider instead painting the covers with washable enamel in rooms that get a lot of use. 

Before papering, turn off the power at the circuit breaker. Unscrew and remove the outlet cover, then apply strips of paper to the wall as usual, papering over the open electrical box. With a utility knife, trim away enough paper to expose the sockets or switch. Replace plastic covers with metal covers for better paper adhesion. 

Prime the cover with wallpaper sizing. Hold the cover in place, and use a pencil to mark it at points where it meets details of the paper pattern.

Cut a 6 1/2-inch-by-5-inch patch of paper that includes those pattern details. Position the cover so that the pencil marks align with the matching pattern details.

Cut the corners of the patch on the diagonal, making sure the pattern matches. Using the knife, score an X over each socket or switch, to make four flaps. Set the patch facedown on a clean work surface, apply glue to the front of the cover, and lay the cover on the paper. Fold back and affix the overlapping edges and scored flaps.

Reattach the papered cover with a screw; camouflage the screw head with a dot of paint that matches the paper pattern.

It is almost impossible to match a pattern at the edge where a wall meets the inside curve of an arch. Fortunately, the eye is drawn mostly to the wall. If your paper has a small, all-over pattern, you can cover the inside of the arch with a single strip of paper, starting at the bottom of one side, continuing through the curve, and ending at the bottom of the other side. More complicated patterns -- especially those with conspicuous repeats -- should be run in two strips that rise from the floor and meet at the center of the arch; otherwise, one side of the arch will be noticeably upside-down. Hang the left half of the inside arch first, allowing an extra 1/2 inch of width for seams and trimming.

Apply glue to one of the strips, and affix it lightly to one side of the arch. Adjust the strip so that 1/8 inch extends over the edge where the arch meets the wall. Also leave 1/8 inch extra to overlap the highest point inside the arch.

Smooth the strip.

Paper the wall adjoining the left side of the arch, overlapping the 1/8-inch carryover from inside the arch.

Standing inside the arch and holding a scraper blade against the wall as a cutting surface, use a single-edge razor to trim the excess off the layer of overlapping paper. Smooth both edges. Paper the wall above the arch and to the right.

Use the single-edge blade to trim the paper flush with the edge of the arch, but leave the paper slightly curled back from the edge. Paper the right-hand half of the arch, leaving a 1/8-inch overlap.

Notch the 1/8-inch overlap where the arch curves, so it will lie flat on the adjoining wall.

Tuck the notched overlap, as well as the straight overlap below it, under the curled-back edge of the paper on the wall. Smooth the seam.

Clean excess glue at the seam with a damp cloth or sponge.

Wallpaper sizing is a premixed sealant that's sold in cans, like paint. Use a paint roller to spread the watery solution on the wall after you have primed it. The resulting surface will make it easier to slide paper on the wall while the glue is still moist and you are adjusting pattern matches. In the future, the coat of sizing will simplify paper removal, should you decide to change patterns or paint the wall.

It's best not to hang a light-colored paper on a dark-painted wall, and vice versa, because the contrasting background might show through minute gaps in the seams. If you cannot avoid an extreme shift in tone, apply a dark or light primer, as the situation dictates.

Every overlapping seam has one hidden edge and one that's exposed. If light from a ceiling fixture, an open doorway, or a window strikes the exposed edge, it will emphasize the seam as a flaw in the otherwise smooth surface. To avoid this unflattering effect, begin papering at the point farthest from the brightest light source, so that the strips' exposed edges will face away from it.

If a seam comes loose over time, dip a small artist's brush in wallpaper-seam adhesive (sold in tubes by wallpaper suppliers), and spread a thin, even coat along the underside of the detached edge. Press the paper back into place, and secure it with a plastic smoother. Remove excess adhesive with a damp sponge. If the edge of a strip is torn, pull back the loose paper on both sides of the tear, coat their undersides with adhesive, gently tamp them back down with your fingers, and flatten the seam with a plastic smoother.