Clean the wall surface
Repair cracks, holes, and loose areas
Scrape off any peeling material
Sand high spots and rough texture
Apply a bonding primer
Skim coat the wall with joint compound
Let the skim coat dry completely
Sand the skim coat smooth
Apply a second skim coat if needed
Sand again with fine-grit sandpaper
Wipe away dust
Prime the wall
Paint the wall with a smooth finish