To level any section or grid of tile, place a long metal straightedge or a 4-foot carpenter's level on the surface and check for any tiles that are higher or lower than the overall surface. Make a beater block out of a 12- to 15-inch 2x4 covered with scrap carpet. Tap high tiles in place using the beater block and a hammer or rubber mallet.
If you discover tiles that are lower than the rest, pry them up with the point of a utility knife and spread additional adhesive on the back of the tile. Set the tile back in place and level it with the beater block. Clean excess mortar from the joints while the mortar is still wet. Run the blade of a utility knife in the joint, flicking out the excess as it accumulates
on the blade. Pick up loose bits of mortar with a damp sponge.