1. Begin by using the same pattern on both sides of the wall. This will make it easier to match up the pattern in the middle.
2. Make sure that you have enough extra material when cutting the pattern pieces to ensure that the pieces will fit together properly.
3. When cutting the pieces, mark the center of each piece with a pencil or marker so that you can easily line them up in the middle of the wall.
4. Use a level to make sure that the pieces are straight and even.
5. Use a thin bead of caulk or silicone to fill any gaps between the pieces and to help them stay in place.
6. Once the pieces are installed, use a damp cloth to wipe away any excess caulk or silicone.
7. Finish by adding a sealer or topcoat to protect the pattern and prevent it from fading or becoming discolored.