Airbrushing does take a learning curve.  I teach classes at my local Hobby shop and the #1 problem that I see when it comes to painting with the AB is that the paint is not thinned properly.  I started long ago with using a AB and thought that I was never going to use my airbrush again after the first couple of times but with more experience it came easier and my avatar is a good example of what I am able to do now. 
Just Dont Give UP!!! 
Cheers 
Chuck