Each coat "bites" into the one before it which is why paint manufacturers list recoat times, if too much time passes a light scuff with fine grit paper is usually all that is required to get it ready, always use a tack rag before painting each coat. As mentioned above glamour paints like shimrin do not have a high hiding ability and finish differently depending on the color of primer/sealer beneath them, some candy colors need to be sprayed over gold or silver for instance, [some colors are better than others at hiding, lighter colors typically poorer than darker]
The above advice is very good if you do not go down to bare metal. Read up a little to make sure your paint[s] are compatable with each other, i.e. you typically don't spray lacquer over enamel or something really "hot" like a catalyzed product.
If you intend to mask go to an automotive paint retailer for their recommendations, many time I use an interclear to not lift the under color before intricate masking.
Some of the custom car paint treatments were discovered accidently be mixing the wrong type of reducer with the paint causing crazing, crackling, and other things. Cobwebbing came about by spraying unthinned paint.
Make sure you have fresh air or possibly a carbon filter mask if you are in a confined space, some toothpicks to pick out bugs, and gloves. Blow off the bike before painting with an air nozzle to insure their isn't any trapped water or gunk, it really is upsetting to make a pass and have some junk come out of a brake boss. Thread a bolt through the derailleur hanger so you use it as a handle to spin it in different positions, sacrifice some bolts for bosses and hangers to keep threads clean, I slip those magazine subscription things that fall out of magazines while your reading them in the bathtub into the bottom bracket and head tube to keep them getting build up inside.
Heh, good luck and post your result.