Fill the nail hole with joint compound using the blade of a putty knife. Press the compound into the hole to fill it. Drag the blade over the surface of the hole and leave a thin skim coat over the hole to allow for some shrinkage as the compound dries.
Allow the compound to dry for 24 hours. Sand the area with a fine-grit sanding block until the repair is completely smooth. If the joint compound has shrunk below the surface of the wall, repeat Step 1 and the sanding process until the outcome is a smooth, seamless hole surface.
Wipe off the repaired area with a tack cloth just before you are ready to touch up the finish. Dab an even coat of primer over the sanded area using a paintbrush and allow it to dry for four hours. Brush an even coat of paint over the primer using a paintbrush and allow it to dry for four hours. Apply a second coat of paint if needed.