Start by removing your shoes when you arrive home. Keep soft-soled slippers by the door, and changing shoes upon arrival will become a habit that not only protects your floor from scratches, scuffs, and pounding, but also keeps your house cleaner.
Floors will still get dirty, just from life. Daily or every other day, sweep using a soft-bristled broom or Swiffer, particularly if you have pets. Weekly, vacuum the floors and all corners with a soft floor attachment.
Periodically you will need to wash the floors -- but do so only if they are sealed. Pick a cleaner made especially for wood floors; aim for a "green" or eco-friendly cleaner for gentle yet effective cleaning that won't leave a chemical smell. Mop gently and quickly; do not allow water to stand or puddle on the floor. Hand-dry with a soft cloth if you don't mind a little on-your-hands-and-knees work.
Do not use wax on a surface finished wood floor. When cleaning no longer restores shine, recoat the floor with a surface finish. The frequency of recoating will depend on the amount of traffic on the floor.
And don't forget to run a humidifier in the winter to avoid dryout.
The National Wood Flooring Association has some helpful maintenance tips.