Repairing holes in your drywall might be easier than you think.
Small holes: Just fill them with drywall compound and scrape. You might need two applications at most.
Larger holes up to 2″. You could cover the hole with drywall tape. First spread a thin layer of compound around the hole, then press in the tape and finish as you would a seam.
Or soak a thin cloth in water-diluted compound and spread it tautly over the hole. With both these methods, take special care to hide the edges of the tape or cloth. Spread the compound a few inches beyond the patch and feather well.
Another method takes a little longer, but can give better results. Cut a piece of screen or cardboard a little larger than the hole. Thread a knotted string through it, shove it through the hole, pull on the string to hold it in place, and use fast-setting patching compound to hold it in place. When dry, cut the string, add successive layers of compound as necessary and smooth it.
If the hole’s bigger than three inches, but no more than 10, cut a triangular drywall patch big enough to cover the hole, bevelling the edges toward the back side. Insert a screw to use as a handle, hold it over the hole and trace its outline on the wall. Now cut out the hole with a matching bevel so the patch sits in place, but won’t fall through. Spread compound around the opening, and insert the patch so it sits about 1/16″ below the wall’s surface. Tape and finish as usual.
If the hole’s any larger, cut a rectangle back to the studs either side of the hole, screw the patch in place, and tape and finish.