Cut the damaged area into a clean rectangle or square
Remove loose drywall and debris
Measure the opening
Cut a drywall patch to fit the opening
Cut and install wood backing strips behind the hole if needed
Screw the backing strips into the existing drywall
Place the patch into the opening
Screw the patch to the backing strips
Apply drywall tape over all seams
Cover the seams with joint compound
Let the compound dry completely
Sand the dried compound smooth
Apply a second coat of joint compound if needed
Sand again after drying
Apply a third thin coat if needed
Sand the final coat smooth
Prime the repaired area
Paint to match the wall
Clean up dust and tools