Dust the walls with a dry microfiber cloth or soft broom
Remove cobwebs from corners and ceilings
Test a small hidden area first
Mix warm water with mild dish soap
Dip a soft sponge or cloth into the solution
Wring out excess water before cleaning
Wipe the wall gently from top to bottom
Rinse the sponge or cloth often
Clean stubborn spots with a soft brush or magic eraser
Avoid soaking painted walls
Use a vinegar-water mix for grease or mildew if suitable
Clean around switches and outlets carefully
Dry the walls with a clean cloth
Open windows or use fans to help walls dry
Repeat as needed for heavily soiled areas