Hello my name is Paul I live in Australia I build fishing rods paint lures service reels etc I like to learn airbrushing like helmet as I'm into pirate underwater theme free hand or stencil
My first piece of advice if you want to paint on helmets, is to work on your freehand technique. Practice the different strokes. All the curves on a helmet make images distort very easily, and it's hard to get stencils to sit right. So freehand, maybe with some hand held shields etc, is def the way to go.
Grab an old one to practice on, to get used to the curves and to practice prep and finishing too.
Enjoy the forum. Come on in, the water's (possibly shark infested, def with a few salty pirates ) fine.