Moisten the wall surfaces with a sponge. Use warm water. Do not soak the drywall, as this can potentially damage it.
Scrape off any remaining wallpaper backing. Use a flat, plastic tool.
Wipe the walls down with a wet sponge to remove all wallpaper glue. Use warm water with a little soap in it. Use your flat, plastic tool if the glue is thick. Replace the water when it gets very cloudy. Allow the walls to dry. Repeat this step until the wet walls are no longer slimy to the touch.
Wipe the walls down with clean, fresh water (no soap).
Open all windows and doors to ventilate the area.
Paint the walls with an oil-based interior home paint. The exact type or brand you use is not important, but it must be oil-based. The paint will collapse most of the bubbles in the drywall surface that form during the wallpaper-removal process. Allow the paint to dry.
Examine the walls closely. Look for areas of drywall paper lifting. Cut these out using a utility knife. First, score around the lifting area. Then gently pry the scored section away. Avoid pulling on the lifting drywall paper surface, as this tends to spread the problem.
Repaint the scored areas with oil paint. Allow the paint to dry.
Fill and cover any noticeable surface damage to the drywall with joint compound. In extreme cases, you may have to coat large areas with successive thin layers of joint compound, allowing adequate drying time between each coat. For this type of project, use a large drywall knife, such as a 10- or 12-inch. Smaller repairs may only require a 5- or 6-inch drywall knife.
Sand down the walls with 150-grit sandpaper to give the surfaces a final polish. The walls are now ready for paint.