On this modified T-Rex project, the blue/grey base color was sprayed first. Then I went back and used a small Badger airbrush for plastic modeling and just freehanded the Olive Drab.
Before you point the airbrush at your plane, take the time to look at and study a lot of photos and develop a plan. Then, take more time to visualize how you can adapt a chosen pattern to your model. It's not a bad idea either to practice a little spraying on a sheet of cardboard to get a "feel" before you take aim at your model.
Patience in preparation of your plan will usually provide the best results. I spend a
LOT of time just looking at my models before and during the painting stages to figure out my next move.