To tile a shower stall, first install a vapor barrier, flashing and cement board to the walls. Make holes for the plumbing and a level line around the stall for the first course of tiles. This line indicates the ending point for the top of this first course of tiles. Apply thin-set to the back of the tiles with a notched trowel, and place the tile firmly against the wall, then continue working toward the ceiling until the job is complete.
The first row of tiles likely requires cuts, since it is unlikely that the level line and top of the shower pan are parallel. Place your first tile in the center of the stall, and work outward toward the edges of the wall. Place each tile with a grout line spacer in between. When each row is complete, set the next course of tile in place. Apply even pressure to each tile as it is placed, to avoid creating lips. Do not apply so much pressure that the notches in the thin-set are compressed. These notches allow air to travel behind the tiles, allowing the thin-set to dry.
Allow two days for the thin-set to dry before grouting the tiles. Apply grout at 45 degrees to the grout lines, ensuring that each line has been firmly packed with grout. Air pockets can cause the grout to crack. After approximately 1/2 hour, remove excess grout from the faces of the tiles with a damp rag. Caulk the inside edges of the tiles where they meet the shower pan, using caulk that matches the grout color.