Use a putty knife to remove any sharp edges sticking out from the small cracks. Wipe the surface debris off the cracks and surrounding area with a dry cloth.
Scoop a dollop of either plaster paste or joint compound out of the container with a putty knife. Use plaster paste for plaster surfaces and joint compound for drywall surfaces.
Cover the small cracks completely with the paste or compound. Use the putty knife to smooth the repair material out as evenly as possible. Let the repair material dry for several hours.
Sand the dried repair cracks with sandpaper until completely smooth. Wipe the area clean with a damp cloth and let dry. Paint the repaired area to match the surrounding wall or ceiling.