Spread joint compound over any cracks, holes or depressions in the wall using a drywall knife. Keep the layer of compound very thin. Let the compound dry for 24 hours. Sand it smooth with a drywall sander. Brush off the dust.
Mark a horizontal line along the length of the wall at the bottom, up from the floor by the height of a tile plus an additional quarter inch. So if the tiles are 5 inches high, the line should be 5 1/4 inches up.
Draw a vertical line up the middle of the wall, from bottom to top, so it intersects the horizontal line.
Spread thin set mortar across the length of the wall, at the base, using your notched trowel. The mortar should fill the wall area between the floor and the horizontal line.
Set the first wall tiles against the wall, under the horizontal line, along one side of the vertical line, so it’s aligned with both. There should be a quarter inch space between the bottom edge of the tile and the floor.
Set additional tiles side by side along the bottom of the wall, under the line, building sideways in both directions. Put spacers between all the tiles as you hang them. Cut the tiles for the two ends using a tile cutter.
Spread additional mortar across the wall, above the bottom course. Hang the next course of tiles, working from the center to the sides. Cut the end tiles as needed.
Repeat, building up the wall course by course with the tiles, putting spacers between all of them. Cover the whole wall.
Let the mortar dry overnight. Pull out the spacers.
Grout the tiles with your grout float, starting at the top and working your way down. Press the grout into the gaps between the tiles, while scraping it off the face with the long edge of the float. Wipe up the excess grout with a damp sponge.