Clean the surface of the tile completely so that your decals will stick to its surface. Use a household tile cleaner with a sponge to scrub the surface clean, then rinse. Dry the area thoroughly with a towel.
Lay out your decals. Use the combination of a pencil, ruler and tape measure to center your layout in the middle of individual tiles, or center decals over numerous tiles if you are working with larger decals or small-bodied mosaic tiles. Mark lines to help guide your decal placement.
Dry-lay decals on the wall before setting them. Use your pencil lines to guide the placement and double-check to ensure that you are installing the decal where you want it to be located. Make any final adjustments to your layout lines, as needed.
Peel the backing off the decal and gently apply it to the tile. Work slowly from one end to the other to avoid trapping air bubbles behind the decal's surface. Work your way across each decal individually to ensure it is properly adhered and lies flat against the tile surface.