Sand the surface of the wall with a 250-grit sanding pole to scuff up the surface.
Wipe the surface of the wall clean, using a tack cloth.
Apply a ¼-inch coat of joint compound to the drywall, using a trowel. Keep the coat as even as you can to avoid wavy lines in the wall. Wait approximately 30 minutes.
Roll over the joint compound lightly with a paint roller. If you press too hard, you will simply smear the compound around. A light touch adds a texture that will hide imperfections. Allow 24 hours of drying time.
Paint the surface of the texture with a latex primer and a paint roller. Do not press overly hard with the roller, or you will break off the tips of the texture. Let the primer dry for 24 hours.
Paint the surface of the texture with a semigloss latex or flat latex paint and a paint roller. Again, do not press overly hard with the roller, or you risk breaking off the tips of the texture. In the event the roller you use does not cover the deeper recesses of the texture, use a paintbrush to complete the hard-to-reach areas.