I use a couple of different Paashce Air Brushes 1 has a #3 needle in it and the other one has a # 5 needle. My air pressure will be between 25 and 32 depending on what I am painting. I usually try to thin the paint down to the same as milk but that don't always happen. Sometimes I just use it straight from the bottle. But that's what works for me, you just have to remember that everybody has their own way when using an air brush.
Jeff