Painting in itself can be a daunting experience. The preparation of the room to be painted is the key to any successful paint job--especially when dealing with wallpaper. This is not an easy project so be patient for best results.
Decide if you'll be applying texture to the area. If so, you'll also need to purchase texturing materials from your local paint supply or home repair store.
Purchase paint, primer, tape, plastic disposable drop cloths, rollers and brushes.
Lay plastic or tarps down over floors and any other surface that may get paint on it. Tape the edges down over floor boards and trim for a clean edge. Take your time to lay the tape down straight and firm.
Adjust lighting to ensure that streaks and lines will be noticed if they should happen to appear while painting.
Remove and tape over light switches and outlets. Set everything aside in baggie or a safe place.
Re-glue any lifted spot in the wallpaper. Check the corners and seams especially well.
Apply by roller or brush a stain blocking, water-based, primer. If the wallpaper is vinyl, you will need to use an oil-based primer. This primer is a thin coat that will stop the wallpaper design from bleeding through the paint. Let it dry according to label instructions. Wash out rollers and brushes with mild soap water and set to dry.
Add texture to the wall if desired. First, let the wall dry. You'll have to seal your texture with more primer before painting. The primer can be tinted to a similar, usually lighter color as your topcoat.
Shake the paint for a minute or two to remix the paint. If the paint has been sitting for a long period, it's recommended to have it remixed at the paint store.
Pour the colored paint into the paint tray. Make sure the brush and rollers are clean. Move the roller back and forth into the tray until the roller is evenly coated with the paint.
Trim and edge the corners and borders of the wall with a small brush and a steady hand. This is where good taping pays off. Allow to dry well and then clean up.
Let the paint completely dry between coats.