I read an article in the paper a week or so ago that said Caldwell Banker did a survey of 300 first time home buyers, and 87% said they wanted a home that was "move in ready". They don't want to see dated wallpaper, worn carpet, worn vinyl floors, bright or dark colors on painted walls. Some sellers feel these are just cosmetic changes, and that the buyer will want to pick their own colors after they purchase the home. Since the housing market is flooded with homes for sale it's important to make a good first impression.
Remove dated or trendy wallpaper and paint the walls throughout a nice neutral light almond with white trim. If the wallpaper is a light neutral colored faux finish it could stay. One last tip, home buyers want to be able to visualize they're own things in your home, so pack-up your personal photos.