If you're doing a colored fiberglass rocket that you intend to clear coat, common practice is to do 4500 or black tinted RocketPoxy fillets. Take your time, do it once, do it right, since you don't want to sand them for shape, only just enough (400 or 600 grit) to give the paint some mechanical tooth.
I'm sure someone is going to come along and call me a paint snob, but for the money spent, can't beat one of these two:
Catalyzed clear, best you're going to get without spray equipment, even has a very high quality spray head. Check out the YouTube videos and decide for yourself. I swear by it, having put it over just about every type of paint out there. Hard, glossy, forgiving, tough as nails. Since it's catalyzed, once you activate it, you spray it, and after 48 hours it's no good to spray any more. One can will do a 4 inch/6 foot rocket with a good medium coat, 10ish minute recoat time, 12 hour full cure.
Pay attention to lot numbers, it has a shelf life of 3 years from date of manufacture. It sells pretty fast, so chances are you're going to get a current batch. Stinks to high heaven, wear a respirator.
Shop around, good bargains can be had on eBay and Amazon.
If you want easy and cheap and easy to repair, go with any automotive rattle can spray clear gloss lacquer.
