This story covers adding base tiles to a room floored with ceramic tile.
Out-of-level floors force you to adjust the base tiles to make their top edges level. You'll make up the difference in the joint at the floor. Lay the bullnose tile against the wall on spacers. Adjust the tile heights with plastic wedges until the top edges of all tiles are level. Make sure the joint at the floor is as even as possible from one end to the other. Continue the layout on adjacent walls. Mark the wall at the top edge of the final layout.
Press tile in place, inserting spacers. Use the plastic wedges to keep the top edge in line. About every 3 feet, use a 4-foot level to make sure the top edge is level. Adjust the tile if necessary by gently pushing or pulling on the wedges. Gently remove excess mortar from the joints with a utility knife and clean the surface. Set and clean corner tiles, and let the mortar cure overnight before grouting.
Grout the trim tiles. Force grout into the vertical joints with a grout float. When the grout has partially cured, remove the excess from the joint at the floor with a utility knife and from the surface with a damp sponge. Sponge-clean the surface at least twice, and wipe off the haze with a clean rag.
Caulk the joint at the floor and along the top edge of the trim. Smooth the caulk with a wet finger or sponge.