This my my simple approach to custmizing, kind of a bang for the buck approach for someone(like myself) who is unwilling to invest in fancy airbrushes, paints and what not.
I've tried a few different brands and Krylon Fusion for plastic is the best thing coming out of a can that I've found............based on Dak's reccomendation for spray paints no less.
The best example I have from my own stuff is my Wasp.(Also the white on my in progress Jazz in Krylon as well.) The green was all Krylon with no other coating. It's very chip resistant but give it at least a week to dry once you have applied all your coats.
And apply your coats maybe 15-30 minutes apart. If you leave it sit to long you'll find that the Krylon doesn't bond well to itself, if at all.
Also I then always spray some Krylon into a little container(plastic butter dish or something) to touch up the areas that the spray missed with a brush.
You'll find that the Krylon drys to the touch fairly quickly and is very chip ressistant, but do try to gve it that week once you've got the coats on.
Once that week has passed I move to the detailing, some with decals, some with Folk Art Acrylic paint. That paint chips very easily(it can be strengthened with an Acrylic paint sealer once done) so is best to not use it on areas like joints that rub.
One can also cheat a little on small details with Sharpie Marker.
The only negative thing I'd say about the Krylon is that I've always gotten the same glossy finish from it which doesn't quite match the look of Hasbro's actual paint.
Examples:
Thundercracker is still in progress but hopefully will give you the idea of what I'm talking about with the different paints I use.
Also in the group shot you'll notice that Thundercracker fits into the general scheme fairly well but Dirge is even a bit more shiny. Thats because I applied the Arcylic paint sealer to the whole figure......If I had it to do over I wouldn't......thats hindsight
....but Dirge was done with the Krylon as well.
Just a warning Rylan, for every project I have that I'm happy with the outcome of I have one thats a bit of a bust. I'm getting more consistent as I go but it can get pretty frutrating at times
You just have to stay the course and see how it goes. Be realistic about your goals. Don't look at Frenzy-Rumble's or TTT work and get down on your own stuff or I think you might sour on the experience real fast.