Brush the area clean. If patching wood, use your finger or a putty knife to fill nail holes or very small cracks with wood filler. For plaster and drywall, use a non-shrinking joint or spackling compound. Using a putty knife, apply a thin skin of filler over the patched area. After patch is dry, sand it smooth. Wipe with a damp cloth to remove dust, then spot prime to create a uniform surface and help the new paint adhere.
Fill larger holes and cracks. For holes and cracks larger than a nail hole, cut two pieces of self-adhesive mesh joint tape, making sure the pieces are larger than the hole. Center the two pieces in the shape of an "X" over the hole and press firmly into place. Cracks usually require a single piece of joint tape. Using a putty knife, cover the mesh with one or more layers of joint compound. When the material is dry, sand smooth and spot prime.