My worth. If you're building the models for just yourself, you can paint them any color and any way you choose. The only person that you have to please is yourself.
I would say that most of the members on these forums paint their models in the colors of the original 1/1 vehicle. Some however build "What-if" models. They are vehicles that were planned on paper but never produced, or just hypothetical versions that they say "What if a certain vehicle were to be built this way, with this armament in these colors." It's all up to the builder. Your the one that has to be happy with the results.
If you have questions about how to paint with brushes or airbrushes, I would suggest you go to the Painting section in these forums. That's where you'll get info on the best ways to paint with brushes or airbrushes and which paints are best to be used.
Hope that this helps. Sit back, relax and build away. Post photos of your builds. Any help you need can be had on these Forums. The members here are very knowledgeable and ready to help out with any questions or problems.
Jim
Stay Safe.
Main WIP:
On the Bench: Artesania Latina (aka) Artists in the Latrine 1/75 Bluenose II
I keep hitting "escape", but I'm still here.