What paint is the best to use on custom figures? I used Testors Model Masters enamel (cause it's what I had laying around, that's why!) and it takes absolutely freaking FOREVER to cure. Is there anything I can do to speed up the curing time that won't melt my figure or my paint job?
Enamels will never cure on action figures.
That is, unless you undercoat with an acrylic primer. Enamel paint has a chemical base that does not bind to the plasticizers in PVC plastic, which most action figures use.
Acrylic paint uses a different chemistry, and so binds to the plastic.
Acrylics are the way to go.
If what you have painted with the enamels has not cured after a day ( it should be dry after an hour or so) then it will NEVER cure and should be stripped and repainted. To strip I've read using Easy-Off oven cleaner.
What tool/brush/etc is the best for fine detail work?
# 00 or #1 grade brushes, preferably a brand name like Winsor/Newton--are good for details.
A #2 or #3 for coverage.
Any other painting tips you can give me?
I adhere to the wisdom of two publications:
Shep Paine's classic " How to Build Dioramas" by Kalmbach publishing ( I prefer the first edition, rather than the later ones), and...
Any of the Citadel Painting guides put out by Games Workshop for their line of table-top gaming miniatures.
Citadel is also the name of their brand of acrylic paint, and its quite good.
Both books have multiple tips on painting, irrespective of their main themes ( diorama building, for one).