For general cleaning, attach a microfiber cloth to a static sweeper and use it to dust your walls once a month. The fibers will grab the dust but the soft cloth will not damage the walls.
If you see scuffs or stains on the walls treat them as soon as possible. Stains left to sit will need a special stain blocking primer.
So how do you remove scuffs and stains - I like toothpaste the best. A little white toothpaste on a damp cloth will remove most scuffs in no time flat.
For greasy spots opt for baking soda on a dry cloth. It will make a little mess on the floor but will absorb the stain.
If your walls need a little repair, don't put that off. Keep some lightweight, quick drying spackle on hand to make quick repairs. Then touch up the paint, feathering out to blend it in with the surrounding paint.
Easy ways to keep your painted walls looking their best! I'm Mrs. Fixit and it's just that simple!