Renters have been known to fill  holes with toothpaste at the end of the lease, and some painters cover holes with masking tape before painting. Better methods for making long term repairs to plaster and drywall are available, and more are being developed. A large hole can be repaired with gypsum board, fiberglass tape and a quick-setting joint compound, and primed and painted in one day using latex primer and paint.  This is a feat you can probably avoid with a little planing.  When filling nail holes sand the hole first with a sanding sponge to remove any loose material, then fill flush with a flexible putty knife or broad knife.  Sand with 100 grit, then generously prime the area with a latex primer/sealer or enamel under-coater.