Painting over vinyl wallpaper requires a few more steps than painting over drywall, but it's a substantially easier project than peeling off the old wallpaper before painting. You won't need any exotic tools or chemicals. If your wallpaper is in perfect condition, you may only need to prime before applying an ordinary interior latex paint in the designer color of your choice.
Wipe the surface clean with a damp cotton rag to eliminate any lingering dust or dirt.
Spread dropcloths over the flooring to protect it from dirt, spackling compound and paint.
Carefully remove any damaged section of wallpaper with a utility knife. Apply wallpaper adhesive to the back of any loose wallpaper so that it is firmly attached to the drywall or plaster surface beneath.
Fill any tears, gaps or missing wallpaper segments with a fast-drying spackling compound; then smooth it to the same level as the wallpaper using a putty knife. Let the material dry completely before moving to the next step.
Use a sanding block to remove any surface irregularities from the dry spackling compound and to eliminate evidence of raised seams. Wipe off the sanding residue with a clean cotton rag or a tack cloth.
Seal the edges of the wallpaper at the baseboard and the ceiling with a fast-drying clear caulk. Wait one hour for the caulk to dry, or as directed on the product's label, before applying a primer.
Apply one coat of an alkyd- or oil-based primer sealer using a natural filament brush or a short-nap roller. Have the paint retailer apply a tint to the primer for improved coverage if the color change from the wallpaper pattern to the planned topcoat is extreme; select a color that resembles the the finish coat. Apply a second coat if the wallpaper pattern is still visible after your first coat of primer. You can paint over most alkyd primers in about one hour.
Apply an acrylic latex paint using a high-quality synthetic fiber paintbrush or 3/4-inch roller. The acrylic latex paint creates a tougher and more flexible coating that can expand and contract without cracking if the wallpaper beneath shifts or flexes. Apply two thin coats of paint, two hours apart or as directed by the product's label. Use a high-quality brush to prevent brush marks from appearing when the paint has dried.