Summarize:

Unless you know your floors are unwaxed, you'll need to test for wax in order to know how to best care for your flooring. Dampen a piece of extra fine steel wool and use it to rub areas you think might be waxed.  Wax will show up as a light grey smudge or smear on the steel wool. Floors that date prior to 1930 typically have many layers of paste wax over a tung oil finish or shellac. You can screen and re-wax the floor or use a chemical stripper to remove the wax and apply a modern polyurethane finish. The easiest and gentlest way to restore an old floor to its former glory is to screen it with a buffer, which can be rented from most hardware stores. After cleaning the floor, use a handheld sanding screen to roughen up the edges and corners of the room where the buffer can't access. Use a buffer with a 150- or 120-grit sanding disc to screen the floor, or buff down the existing finish.  Sanding pads are color coded, with black, purple, and brown being abrasive stripping pads. Green and blue are mid-level abrasive, and tan and white pads are mild polishing pads. The sanding discs will wear out, so you'll need at least three to screen a typical room. Buffing will not remove deep scratches or heavy damage. It will, however, help restore shine and remove surface scratches to old or dull hardwood. . Once you've finished buffing, wipe down windowsills and other surfaces and vacuum the room thoroughly to remove all dust. Your choice of finish will depend on the results of your wax test. For waxed floors, apply paste wax. If your floor was finished with a modern sealer, go with polyurethane. You can't use one if you started with the other: don't apply wax to a polyurethane finish or vice versa. If your floor is more than 50 years old, you should avoid sanding it. There's a limit to how much wood you can remove without permanently damaging the floor. When cleaning and reviving an old hardwood floor, sand only if it's so heavily stained that screening or chemical stripping aren't options. Get professional help if your old hardwood flooring is seriously worn or damaged, or if you're unsure about its composition. Word of mouth is typically the best way to find a good contractor. Look for one with restoration experience who won't advise you to simply rip out the entire floor unless absolutely necessary. For example, if your floor needs patching, you could have an experienced contractor remove flooring from a hidden spot, like a closet, and use it to replace a worn or damaged area.
Test for wax. Screen your floor with a buffer. Refinish your floor Avoid sanding old hardwood floors unless absolutely necessary. Consult a professional with restoration experience.