Wow, what kind of paint do you use?
Typically, I use rattle cans, mainly Krylon Fusion (though the lime green Metroid one was done with Valspar Plastic Paint - which is nice, but very limited colors available - at least in my area - and has a tougher to use spray nozzle). I don't have a great deal of decent paint options in my area and after trying most of them, found that the Fusion offers the best combination of price, durability, and vibrancy of color. Some people don't care for the way it comes out as it doesn't really give a shinny, super smooth finish all the time (I actually prefer the slightly duller look myself, so that's what I usually do on custom projects), but I've alway had pretty good luck with it. Except for the yellow. For some reason, everytime I've used the yellow, it's been thin and runny. Very hard to work with. I don't usually use a primer with it as I've found it doesn't seem to make much of a difference whether you do or not. Instead, I lay down a thin, but fullly covered layer of color, which sort of acts like a primer. After it dries for a week, it gets another, thicker layer of color and then a clear coat. I would advise anyone NOT to use the Krylon Fusion Clear Coat though. I don't care for it at all. I use a normal Krylon clear coating which seems to work well. just be careful not to layer it on too thick or fast.
And honestly, I've found that the most important part to any custom paint job is the pre-painting preparation. Make sure you wash all pieces to be painted thoroughly and be sure that they're completely dry before actually painting. Pre-Painting prep solvent helps as well.
If you're interested in your own paint projects and would like a how to guide, check out Wiggy's blog. He's got an excellent step-by-step guide all about painting plastics that I've found to be very helpful.
