While the smaller tiles that make up the mosaic will be more forgiving of a gradually sloping substrate, such as the floor of a shower, it is still important to ensure the surface you're tiling onto is clean, dry and flat. Patch any holes or cracks. If the surface beneath the mosaic tiles is too uneven, those imperfections may start to cause the tiles themselves to look unevenly spaced. In wet areas like bathrooms, shower surrounds or kitchen backsplashes, use a backer board or waterproofing membrane.

Measure the area where you will be installing the mosaic tile. Using these measurements, dry lay the mosaic sheets to plan the layout, accounting for any cuts needed around outlets or edges. Mark your layout lines on the prepared surface using a level and straightedge. This plan will help you determine where to lay your first mosaic sheet as well as how the edge tiles will need to be cut.

For most tile sheets, you should be able to simply cut the mesh backing between the tiles. To cut the mesh backing, flip the tile sheet so the tiles are facing down and cut the mesh using a utility knife.

Using a level, mark a line on the wall where the bottom row of your tile backsplash will be. Then, using finishing nails, attach the ledger board to the wall using the line you marked to keep it level.