BEFORE YOU START HARDWOOD FLOOR REFINISHING, CONSIDER THE COMMITMENT!
When sanding wood floors if your floors have any buckling, high spots, warping or waves, you definitely want to sand those completely flat with a hand sander or belt sander before you can even start using a drum floor sander. Depending on how bad it is, you may decide that refinishing your hardwood floors is just not worth it.
Remove any staples or nails from the flooring. If your hardwood floors have been painted, you may want to strip the paint before sanding.