If your walls are old and worn, a new coat of paint could freshen them up. However, painting over imperfect surfaces won't hide certain blemishes. Divots, bumps and cracks will all show through new coats of paint. When painting an imperfect wall, good surface preparation reduces blemishes for better-looking results.
Fix any large cracks or divots using patching plaster and a putty knife. Slather on the plaster, and smooth it out with the putty knife. Wait for the plaster to dry.
Sand recently patched and existing bumpy surfaces with 150-grit sandpaper. Sandpaper helps smooth rough surfaces for more even-looking paint coverage.
Clean the surface with trisodium phosphate. Old wall surfaces are often covered in dirt and dust. Trisodium phosphate cleans the wall without leaving behind any residue that could react with fresh paint.
Prime any recently patched areas using a paintbrush and general purpose primer. This is called "spot priming," and it helps paint cover better over plaster patches.
Cover trim and wall fixtures with painter's tape.
Paint the wall with flat latex paint. Latex paint works well on wall surfaces, and a flat finish does not show imperfections as prominently as a glossier finish. Paintbrushes are ideal for edges, and rollers are useful for large wall surfaces.
Paint a second coat after the first layer of paint dries.
Peel off the painter's tape after the final coat dries.