Divide your backsplash design sketch into a grid of squares no bigger than 1 foot each. Number the squares, so that you know the order they go in, then cut the design into squares with scissors.
Cut squares of fiberglass mesh to the same size as your design squares.
Lay a design square flat on a work surface and place a square of fiberglass mesh on top. Stick on your mosaic tiles using mosaic adhesive, following the design underneath the mesh, and ensuring a gap of approximately 1/8 of an inch between each tile.
Place the tiles on the grid with tweezers if they are very small. Unlike regular tiles, mosaic tiles are held in place primarily by grout, so the adhesive is used to set the layout and to keep the tiles in position while you grout.
Repeat on all the design squares so that you have the entire backsplash mosaic done. The layout of your backsplash is now complete.
Remove the design sketch from behind the fiberglass mesh so that it doesn’t get stuck there, and place it gently on top of the mosaic so that you know the square’s sequence in the design.