Patching nail holes, hairline cracks, and large holes in drywall is a fast and easy job. You will need spackling compound, a lead pencil, a putty knife, white glue (for patching large holes), fine sandpaper, and paint that matches the wall.
To patch small nail holes, insert a punch or the lead of a sharpened pencil into the hole and push the pencil inside. What you are doing is pushing the broken paper covering the gypsum board into the core so the patch will fill the hole properly. This trick is easier than trying to peel back the paper covering to try and make a smooth patch. Spread the spackling material over the hole with a putty knife and then scrape the excess off the wall with the tip of the tool. When the spackle is dry, sand the patched area with the fine sandpaper and you are now ready for painting.
If the holes and cracks in the drywall are large, thread a piece of string through the center of a piece of cardboard. The cardboard should be slightly larger than the hole that is to be repaired. Cut away any loose gypsum and paper from the edges of the hole. Now take white glue and put a bead of glue around the outside edge of the cardboard, about /2" wide. Put the cardboard through the hole and with the string, pull it flat against the back of the drywall. The glue on the cardboard will stick to the back of the drywall. Tie the string to a pencil and hold the cardboard in position until it holds. Now you can fill the hole with patching compound. Let the compound dry for several hours. Once it has set, cut the string off and patch any irregularities. Let the surface dry completely then sand with fine sandpaper. Your newly patched wall is now ready for a coat of paint.