Auto body repair & detailing: Painting Fiberglass, scotch brite pad, fiberglass resin

Question
I had to repair some rust holes on the edge of my rear fender well.  I decided to use fiberglass, it looks great and now I'm ready to paint.

How do I prepare the surface for painting?  I've heard from some that I should put on a thin coat of Bondo, others say just sand smooth and put on layers of primer until any pinholes are filled.

What do you think?

Answer
First of all, did you remove all of the rust that was under the fiberglass? If you didn't that is going to be the first problem. Rust is like cancer it eats thru everything, even expoxy fiberglass. As far as being ready to finish, I suggest a thin coat of icing or if you do not have any, use regular body filler and mix in about a tablespoon of fiberglass resin with it and it will thin it out. The skim coat is meant to fill in any pin air holes and any scratches that may not be noticable. After this is feather edged out scuff the rest of the panel with a scotch brite pad or blending paste. Then prime with a in expensive laquer primer and splatter a dark paint over it as a guide coat. Wet sand with 400, tape and apply 3-4 coats paint then clear with 2 coats evenly on the entire panel. Hope this is detailed enough. Email me with any questions.