Wood floors have a rich sheen. Colour choices run the gamut from pale, almost white, to ebony. Patterns include parquet, herringbone and planks. Most modern wood floors have been treated with a finish to protect the wood. Your first step is to determine what finish your floor has. Waxed floors are cleaned differently than floors with a urethane finish. Varnished floors should be treated the same way as shellacked, lacquered, untreated or penetrating seal treated floors according to Christopher Davis of the WFCA -- the Wood Floor Covering Association.
Vacuum the floor using an attachment for flat surfaces and not the beater bar for carpets.
Pre-treat crusted on dirt and food with a solution of oil-based soap and water. Follow label directions. Soak a paper towel in the solution and leave on the dirt or food until it comes up easily. It will probably only take 10 minutes or so.
Fill a 2-gallon bucket with warm water and oil-based soap per label directions. Dip the mop in the solution and wring out until almost dry. Mop the floor. Use an old rag dipped in the solution and wrung out to get into the corners.
Dry the floor with an old towel as you go. The varnish protects the wood so you're actually cleaning the varnish not the wood. However if there are any scratches in the varnish the water will penetrate to the wood. Drying helps prevent the penetration.
If floors are very dirty, repeat the cleaning several times letting the floor dry completely in between.
Don't soak the floor. Don't use detergent based cleaners or ammonia. Don't wax over the varnish or use vinegar.