Anthony it would probably be easier to just buy a gallon of this somewhere, and just shoot it on the outside of your car.
Preping is the key. If you slack on this whatever you are painting is going to show it.
I took the plastic and washed it down with some goo gone. I did this to take any of the oil and factory paint film off of the plastic. (be careful on some plastics it may melt it and cause more harm than good)
I just used an abrashive sponge to get the film off and scrubbed.
Than i washed it all down to see if i missed any spots. If all was good than onto sanding. 400 grit wet or dry. Sanded until i couldnt see anymore scratches and it felt smooth. I made sure to get into little cracks and the small details. I would sand it dry first, than wash it. Sand it wet, wash it, sand it wet then wash.
No onto 800 grit. Same process as the 400.
Made sure it looked good and i couldnt see anything else that needed sanding.
I dryed the piece.
Sprayed, let it sit for 5 minutes, sprayed a second coat on it. Came back in another 5-6 minutes and it was able to be handled.