Painting Prep Tips
Remove small objects from the room; gather large ones in the center and cover with a plastic drop cloth. Unscrew switch and outlet face plates. Lay masking paper over floors and tape as shown below. Protect carpeting with canvas drop cloths.
With a flexible putty knife, apply spackling paste to nail holes in the wall and wood filler to small cavities in trim (overfill slightly, as compounds will shrink). Let dry completely, then sand using a medium-grit paper on walls and a coarse-grit one on wood.
Cover crevices in the wall with self-adhesive fiberglass-mesh joint tape. Apply a thin layer of joint compound over the tape with a flexible taping or joint knife; work quickly to smooth before the paste dries. Lightly sand with a fine-grit paper.
To fill cracks between the baseboard -- or any trim -- and the wall, apply latex caulk (which can be painted) with a caulking gun, following the manufacturer's instructions.
Immediately after applying caulk, use a damp sponge to even it out and wipe off excess. (It is impossible to do this after caulk dries.)
Cleaning & Priming
Vacuum the room and wash walls with a sponge and warm water. Tape off the ceiling, then prime walls. If you'll be covering a light-colored wall with dark paint, use a gray primer, or have one custom-mixed to match your paint shade.
Line the perimeter of each pane with painters' tape, leaving 1/16 inch between the edge of the tape and the muntins. (When painted, this will create a seal that prevents moisture from getting in and rotting the wood.) Remove locks and other hardware, and clean wood with a tack cloth.
Keep these items in your paint cleaning arsenal: liquid dish soap for washing brushes, a brush comb for removing persistent particles, sponges and rags for wiping surfaces, and a razor blade for scraping windows.