Showing a comfortable way to hold the airbrush and how to gain better control using two hands.
Think of the index finger as the driver, the middle finger can be your funny passenger and your thumb is the big guy who sleeps and stays there for support.
In this way the index finger is what drives your airbrush, it controls the trigger action, double actioning correctly by holding the air down (and keeping it down) while pulling back for paint flow.
Your second hand is used either to support your hand doing all the work or to maintain a distance between the airbrush and your artwork. We’ll call this distancing.
This is important to maintain the correct distance while pulling off any effect with the airbrush. Unless it a raising effect you want to make sure that you are distancing correctly from the artwork at all times.
It means that you’ll have more control over your artworks and also steadies your airbrush hand. This practise can be seen in all of the airbrush tutorials, unless texturising the artwork.