Hello Nachos, and welcome to the 'Drome.
There are certainly some very skilled modelers here, and I'm sure they each have a unique way of doing things.
Personally I paint with brush. I don't have an airbrush, and I don't really believe in them for WW1 models. I paint with preferably Polly Scale acrylics. These are very nicely flowing and painting in several thin and thinned layers give a fine result.
Painting a Nieuport in linen colour, it may be best to mix some light grey in the first couple of layers and then finish it off with a couple of unmixed layers.
Good luck, it's a grand hobby.
Thanks for the link on the Nieuports, Stephen.
Thanks.
Kofoed