Hoovering your wood floor as frequently as possible you will prevent hard grit or sand from making nasty marks in your wood flooring. If you sweep rather than vacuum, make sure you use a soft brush so you don't drag any of the small stones etc that get brought in on shoes, over the wood.
If you come across any stubborn stains or marks on your wood floor, remove them by dry mopping. So just use a regular mop that is just damp, too much moisture can really damage this type of flooring so if you do have any spillages try to soak them up as soon as possible.
To avoid making permanent marks on your floor, make sure you use furniture pads on the feet of any furniture you have. a piece of felt will do the trick, just cut it to the right size and glue to the base of the legs. Obviously you should try and avoid dragging any furniture across wood floors but the felt will help to minimise any damage.
For high traffic areas, such as hallways and routes though rooms, consider floor runners or rugs to give the wood flooring some protection and to prevent any area specific wear. This will maintain the overall look, condition and colour.
Sometimes it's worth considering getting a professional in to spruce up your wood flooring. Most manufacturers recommend periodic waxing and buffing and if it needs more than that, the floor can be sanded back and re-finished to restore it to it's original glory!