You can prepare new floors from your wood floors, concrete floors or old floors too, if they are in the sound condition. Before relaying you floor inspect it carefully and fix any faults if you find some. You can re-glue the tiles that have shifted from their place. You can level your uneven wood floor with the help of a plane or sand. If your concrete floor is suffering with the problem of moisture you can fix that by using the anti-moisture chemicals and then putting a layer of particleboard or plywood. But be careful to check for any molding before installing the new layer over your existing concrete floor