Having done this a lot during my Graphics course, I'll lend you a few tips:
<ul>[*]Be sure to use a primer on the surface of your piece to ensure there's a decent base upon which to spray the proper coat. Without this there's a good chance you'll find the final coat won't 'hold' as well to the surface.[*]Test the paint out on a small area first, before you go ahead and cover the entire lot. If the paint doesn't 'hold' to the surface well, or if it cracks upon drying, try a different paint.[*]Be sure to get as even a coat of paint as you can - this reduces your workload on sanding down smooth later on. You can remove any dribbles or build-ups with wet-and-dry sandpaper (ask your local craft store or DIY store, they should have it).[*]It's been said before, but please, make sure you spray in an open area with good ventilation and a mask. As much as we'd love to see you in your armor, we don't want you to end up in hospital from inhaling the fumes from the paint. Safety first, ALWAYS.[*]After you've sprayed it, seal it. Talk to the store owners who sold you the spray paint, and they should know which sealant to use. Again, follow the steps above by making sure the sealant 'holds' to the paint, that it won't react badly to the paint, and that you get a good, even coat over it.[/list]
Do all of this and you'll have a good, clean set of colored pieces to wear. Good luck!