First I cleaned the snot out of it, degreaser, and since I was not sticking to stock colors, lacquer thinner to stubborn spots. Blew it dry and then looked for scratches I could sand smooth. I did not need any filler, there were no deep scratches.
Paints were rust o leum paints for plastic. Just taped off and took my time. I can't tell you how many hours I have in it.