Clean Tile with tile cleaner thoroughly; let dry completely.
Use Chip Filler to fill in any gaps in your grout or tile. It will dry in 10 minutes.
Tape off any portion of the shower wall surface that you do not want painted.
Scrub tile with steel wool and rinse with water. Repeat as many times as necessary to create a distressed surface. Essentially you are scoring the tile so that the paint adheres to the tile perfectly. Let dry completely.
Apply first coat, starting from the left and working your way over. Allow that first coat to dry completely before you star the second.