I've never had a hard time tinting car windows, or even my house windows, although the flatter the glass the better and easier. Just never use Dawn dish soap and never use Windex/Ammonia based cleaners but DO start with a clean surface. Vinegar works real well for this. Also, to separate the film from the backing, use 2 tiny pieces of scotch tape, one on both sides, and pull them apart. Also, I work in the paint and graphics department at Polaris industries and have applied decals and such to literally thousands of motorcycles and know what works, if I didn't, I'd probably be fired. Use the SOFTEST squeegee you can get your hands on, spray the surface you are going to squeegee with your soapy water in addition to the sticky side, and don't use too much pressure when pulling the squeegee. This stretches the film and can cause it to have curls and ridges when it dries. Nice, steady, semi-lite strokes, keep respraying with soapy water if it starts to pull from drying out.