make sure you use the little bottle of spray that comes with kit, wash hands many times and clean surfaces off. as you peel off backing spray the sticky side of the film as you peel it as well as the surface its going on, keep fingers wet until your sqidying. a warm day or workshop is best and use hair drier to soften the film. if its not going to plan it will usually just pull back off with a yank if its not been squeezed on. if you get little bubbles just pull it back off and spray again, this can be done over and over again. i usually start with a small piece to get into the swing of things.
i didnt do this tank in pic myself as had it fit at BMW but have done many myself.
