Take your first tile and line it up so that it's flush with the edge of the shower base and follows the pattern of the bathroom tiles. Using your spirit level and pencil, mark the line where it will need to be cut. This line will match the line marked on the shower base floor. Use the tile cutter to cut the tile. Lay the two parts of the cut tile back into shower base and mark out where they will need to be cut so that they fit around the drain cover. Cut the tiles to shape.