What is the best way to fix a hole in your floor

Jenn76, there are holes and then there are HOLES. If it is just a relatively small hole I suggest a piece of sheet metal that is in size bigger than the hole, no less than an inch or more bigger. Use a 12 or 14 gauge piece of sheet metal. Place the sheet metal over the hole and drill a few holes through the outside perimeter of the patch. Then use some pop rivets to fasten the patch to the floor board. This shows how a pop rivet works. Harbor freight and other places sell the pop rivet gun for something like $10 and the sheet metal should be available at a good hardware store for only a few $$. Now, if it is a HOLE then consider replacing the floor board with a commercial made repair panel. Not to expensive, check on here, but they will require some welding. Check on here for a floor repair. Hope this helps, good luck.