One good coat of primer should do. Then you need to top that with sealer before you put down your actual paint. If you have no sealer to put down then slap on another coat of primer to make sure ou have a uniform color and then wet sand that with 1500 or 2k. Then your ready for the paint. If you are useing spray cans you will need to get in a well venilated area, but with absolutely no wind. Not even and angel fart can blow across your work. With the spray bomb you want to go with quite a few light coats called dust coats. Reason is that if your not extremely careful you will get runs rather easily. Very important to remember to clean the surfaces thoroughly. May i suggest you spring for the the "prep-sol" or preperation solvent.***Only use on pieces you are about to your base coat to. DO NOT use on a painted surface be it base or clear.
Remember, follow the contour of the piece you are painting always remaining 6 or more inches away from the surface. It is better to suspend the pieces in the air if possible. Wire coat hangers are great for this. Having them laying down of flat surfaces can create many issues i just can't cover in here.
If you are useing a gun then you should have a pretty decent idea of how to apply paint. That's the easy part. The clear is what can get ya. Just relax, take your time, and have fun. If you mess up its no big deal. Just set in sun to dry, scuff, and spray again.