I Have Wood Floor In My Bathroom What Is The First Step That Need To Do In Order To Lay Tile Down?

  You could skim the top of the wood floor with a self leveling compound and let it cure, (set up), for 48 hours before laying the tile. You can purchase it at most home supply stores. It is a concrete mortar mix. Just make sure to cover all the wood and level it out. The thin-set will stick to the leveling compound and provide a better bond for the tile, or you could screw backer board down over the wood and then lay the tile. If you go with the backer board, be sure to take the height of the door from the floor into consideration.