Deep Cleaning: Dirt, oil, and grime build up over time and aren't completely removed by a weekly dust mopping. For occasional deep cleaning (consider doing the cleaning in the spring or just before the winter holidays), use a wood-cleaning product diluted according to the label instructions. Saturate a sponge or rag mop in the water, then wring it almost dry so it feels only slightly damp to the touch. Damp-mop the floor with the grain of the wood, being careful to prevent standing water on the floor. Rinse with a clean mop dampened in clear water with the grain of the wood, but only if the cleaning product requires it. Wipe up excess liquid because standing water can damage wood surfaces. If the weather is humid, operate a ceiling fan or the air-conditioner to speed up drying.
Removing Marks: Consider your floor's finish before trying to remove a mark. If the stain is on the surface, your floor probably has a hard finish, such as urethane. If the stain has penetrated through to the wood, the floor probably has a soft oiled finish -- common in older homes whose floors have not been refinished and resealed. Wipe surface stains from a hard finish with a soft, clean cloth. Never use sandpaper, steel wool, or harsh chemicals on such a surface because they can permanently damage the finish.
The following remedies are for hardwood floors with soft oiled finishes. If needed, end each treatment by staining the wood, then waxing and buffing the spot to match the rest of the floor.