Find out which surfaces are safe to scrub with water.
Before setting sponge to surface, consider what your wall is covered with. Avoid washing flat emulsion paint, which can be damaged by water. (Jeff Bishop, a technical adviser to the Institute for Inspecting, Cleaning, and Restoration Certification and the president of Clean Care Seminars, suggests a dry-cleaning sponge as an alternative.) But for gloss paint and most wallpapers (except vintage or antique ones; check with the manufacturer if youre concerned), a DIY cleaning is good to go. Its always best to test in an inconspicuous spot first.