1. Stop dirt at the door. Grit stuck to the bottom of shoes is a finish-killer. To keep from tracking it in, place doormats at entries and tell people to take off their shoes. Ban high heels and soccer cleats; they can dent floors.
2. Prevent scratches. Put felt pads on the bottom of furniture legs. Clip dogs' toenails.
3. Keep it clean. Vacuum regularly. Follow up by mopping with a moist microfiber pad. Wipe up spills promptly to prevent water from warping boards or damaging the finish.
4. Renew the finish. Brighten a dull surface with a light sanding and fresh coats of polyurethane. Do this "screen-and-poly" every few years—consider setting up a maintenance plan with a flooring pro—and you may never need to refinish.
5. Beware of buildup. Avoid cleaners that contain ammonia, vinegar, wax, polish, or oil soaps, any of which can dull or etch a top coat and cause refinishing problems down the road. Not sure what's in your cleaner? Do this test: Spray it on a window and let it dry. If it leaves a residue or an oily film, toss it.