Advice needed for cleaning wood floors

Having recently had 2 floors sanded I now want to know how to keep them looking beautiful!
The professional who sanded the living room advised against washing the floor as the water was bad for wood. What am I supposed to use? I can vacuum it but it will get dirty.
He put a couple of coats of varnish on.
The other floor, which we sanded ourselves, we treated to a coat of osmo wood wax. It's a bedroom so won't get so dirty but I would rather not damage the wood.
What would you do?