I will reiterate, VERY VERY LOW AIR PRESSURE!!!!!!! I also start spraying about 2 1/2 to 3 inches out and bring it in slowly to the center of the decal. I had it blow a decal up away from the model one time. Luckily the decal had not softened yet and I was able to quickly correct the situation with some water.
And this is one of the wonderful things about being a part of MA!
Oh and edit to add this. I also use a needle valve to regulate the air pressure right at the airbrush. Gives a lot more control than just the moisture trap control on the compressor.
I use Badger airbrushes with a Badger/Paasche adapter, Paasche needle valve, and Paasche hoses with a moisture trap about 18 inches from the airbrush.
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Hope this helps. The needle valve makes a huge difference even just for spraying paint or much anything else. My regulator is set at I think 25 psi, but the needle valve is where I actually control the air flow.