There's a story about a fellow driving down the streets of New York City, and he sees a musician carrying his intstrument with him as he walks. He waves and stops the gentleman, and asks, "Can you tell me how to get to Carnegie Hall?" The musician replies, "Practice, practice, practice."
In a nutshell, that's what you need to do: build and practice. As a suggestion, I would post any specific questions about colors and camoflage you may have in the armor and aircraft forums. You'll find a ton of folks who will be glad to help you out. For specific airbrush questions, come here. Our resident airbrush expert, MikeV, can answer your particular questions on the airbrush, and the rest of us will jump in with paint recommendations.
Lastly, (maybe this should have been first) do a search on your particular questions. Could be that it has been asked before.
Good luck, and welcome to the forum family!
Gip Winecoff