Any area that will be exposed to lots of water during this how to tile a shower wall task should be coated with two coats of a brush on waterproofing membrane available at some home centers and all tile stores.
How to tile a shower wall with a window.
As with all tiled shower installations run cementboard throughout the shower area and on the same plane as the window jamb.
This video shares tips for how to tile a shower wall using subway tile.
That way you can make sure the grout lines of the recess are on the same plane as the wall.
Caulk the joint between the jamb and the cementboard with a good quality silicone caulk.
Use disposable brushes and let the first coat dry thoroughly before recoating.
Install tiles around the window by spreading an even coat of thinset with a comb trowel.
Use bullnose tiles to round off the edges of the window frame and tile the wall first.
Line up a tile with the edge of the window and protruding out over the full sized tiles on the wall.
Afterwards install the bathroom tiles and place spacers between them as shown in the image.
Secure the tile edging into thinset and use a large level to make sure it is plumb.
Mark the tile where it overlaps the full sized tile and number it on the back side.
You can expect to spend about four to five hours tiling a standard 36x40 inch double hung window.