Step 1: Gather Calligraphy Supplies
Ink is readily obtained at most art-supply and stationery stores; black is traditional for invitations and formal correspondence. Gouache is a type of opaque watercolor paint that you mix with water (aim for the consistency of cream); it can be used as an alternative to ink, which can be translucent on colored paper.
Pen holders (handles with metal ends to hold the nibs) can be straight or oblique; try both kinds to see which works better for you (oblique may be more comfortable for right-handed writers). Fit the holder with a nib, or tip. A nib's concave, split design makes it flexible, allowing you to make thick and thin lines.
Guide sheets have horizontal and sometimes diagonal rules that help you space letters and align them consistently as you learn. On the final products, use a ruler and pencil to make lines on your envelopes or other paper; erase after the ink dries.
Paper should be a plain-finish stock with a smooth, flat surface; ink smears on shiny stock, and the nib can skip or catch when pulled across a richly textured paper. You'll also need a blotter to rest your pen and catch drips; you can use any soft cloth.