Stenciling is one of the oldest and easiest decorative painting techniques. Use it to create borders of various patterns on walls, ceilings, floors, and around windows and doors. Stencils look like the reverse of a coloring book page, with spaces where the pattern would ordinarily be. About the size of a sheet of typewriter paper, reusable stencils are made of thin plastic or heavy paper. They're available at art supply stores or retail paint outlets.
You can make your own stencils, too. Use thin cardboard -- shirt cardboard is fine. Sketch a design, transfer it to tracing paper, and cut it out with scissors or a craft knife. Lay the pattern on a piece of cardboard slightly larger than the pattern itself, trace around it, then cut it out.
To transfer your design to the wall, tape up the stencil at all four corners. Use a special stenciling brush -- usually round in shape, but flat across the bristles -- to apply latex or alkyd paint to the cutout. Pour paint into an old saucer or pie tin. Dab the brush lightly into the paint, then dab it lightly on kraft paper to remove excess paint. You should be working with an almost dry brush. Don't stroke the paint on the stencil. If you do, you'll force the paint under its edges. Instead, use a light up-and-down dabbing motion. Let the paint dry to the touch, peel the stencil slowly away from the wall, and move on to the next area.
If you want to create a border using the same pattern over and over again, it makes sense to buy or make extra stencils so you can continue to work on other areas as the paint dries on the first ones. If your stencil requires two or more colors, paint with only one color at a time and let the first dry before adding the second.
Plastic ready-made stencils are washable and reusable. Those made of heavy paper or cardboard, however, will only last so long before the paint saturates the fibers and weakens the stencil. When that happens, buy or make new ones so that the stencil stays flat against the wall as you paint.