Spread the Adhesive Onto the Wall
Since the tile is going on regular drywall, not cement board, use pre-mixed ceramic tile adhesive, or mastic, instead of thinset. The mastic doesn't set immediately so its easier to work with. Spread it on the wall with the 3/16th V-notch trowel (Image 1). The top of the tile follows the level line all the way across for a uniform look (Image 2). This leaves varied spaces on the bottom, so use plastic shims to make up space. Line up the next sheet so it fits perfectly, leaving a space between the two for a grout line.