Pretty much the same for me as what artic fox said.
Except i used a pressure washer to clean mine.
I washed it, wire brushed the hell out of the chassis, welded where it needed it, washed it again, let it dry for a couple of days then it was 2 coats of red oxide primer followed by 3 coats of manor chassis paint.
Forgot to add....... Admittedly i did have the body off the chassis at the time which made life much easier