The wood becomes like that because of moisture, so if you are using wood/homogeneous tiles do use a tile sealer
 
	You can seal your tiles by using something called HCL89.
 
	I usually get it from http://hcl89.byethost10.com or http://hcl89.atwebpages.com
 
	What it does is that it removes any stains as well as polishes your tiles and seals it. The tile sealer is important because it prevents moisture from damaging your tiles in the long run
 
	Hope this helps you out