You need to prep the area very well.As with any paint project, proper adhesion and application is in the surface prep.You will need to make sure you get ALL dirt,grease,armour all/vinyl protectant off the surface first, otherwise it will flake off or "orange peel/fish eye".Hold the can away at the recommended distance or about 10-12 inches and spray in a horizontal direction and then wait a few minutes for it to tack up and then spray in a vertical direction.Repeat several times to get complete coverage you are satisfied with.Do not try and get complete coverage in one shot,you may just make a big mess that will be very difficult to correct (ie: runs)Don't worry about complete coverage the first time around.Take your time and do several light coats.You can save yourself quite a few $ by doing this but preperation and patience is key.
Use the "VINYL" dye in a rattle can.Good luck.

David