For a quick fix, I usually shove some toothpicks or used matches with a decent coating of wood glue in the hole, let it dry for a bit, then put the screw back in.
Dip a toothpick in wood glue,put it in the hole then snap it off flush. Repeat this until you can't get any more picks in...once it's dry use a razor knife to cut them all flat. Then just screw the screw in. It's easy.