Over the years, I have used toothpicks, steel wool wrapped around the treads, epoxy, and wood glue to fix stripped holes. They all work if holes are not too stripped. What I do for larger holes is to cut a triangular piece of wood out of the corner of flat oak pallet board with a knife. The knife will follow the grain of the wood producing a tapered triangle piece. The triangle piece of wood is tapped into the hole and the over sized triangle will bite into the hole preventing the screw from spinning.
