To dust papered walls, tie a dustcloth over your broom and work from the top down.
To remove pencil marks and other non-greasy spots from non-washable papers, use an art-gum eraser or a slice of fresh rye bread.
To remove greasy spots, crayon marks and food stains, apply a paste of cleaning fluid and fuller's earth, cornstarch or whiting. Let dry and brush off. Repeat the treatment until the spot is gone.
Wipe off fingerprints with a damp cloth, then sprinkle the moist area with fuller's earth. Let it dry and then brush it off.

To prevent splash marks when you're washing baseboards or other woodwork, mask wallpaper with a wide ruler, venetian blind-slat or a piece of rigid plastic.
When you save scraps of wallpaper for patching, tack them to a wall in the attic or closet. When you use them for repairs, they won't look so brand new.