Good Morning, Ray...
Using an airbrush has its own list of variables. I find myself spraying in a minature technique of the way that I use a quart cup spray gun in my line of work. First, you really do need to have a good air supply...it makes all of the difference. If your air pressure is too low, you'll find yourself spraying too close to the model to get coverage and run the risk of sags and drips. For years I used one of those oil-less, table top, noisy jobs and it did the trick. I adapted my spraying technique to it, set my air brush up for its output, and used it on many models. Then, one day, Sears had a sale on a 1.5 HP little tank compressor with all of the fittings. SOLD! I made certain that I also bought the air/water seperator, too. I spray solvent based paints using an old Paasche model H airbrush. Using 20 lbs. of air pressure, I usually spray at about 4 inches from my surface. I have my airbrush set up for a certain pattern. Using the volume adjustment, I set the airbrush so that I get a 1/2" +/- spray pattern. I never try to get the most coverage all at once. That will lead to places where the paint is heavier or lighter. I also don't move quickly or look at the airbrush. Instead, I watch the paint as it goes on the surface moving further or closer, faster or slower as needed. I paint in overlapping passes, too. Just enough overlap to cover. Paint needs to be thinned for spraying, too. I cut my enamels with acetone by about 1/3 and ALWAYS test my mixture and airbrush setting on a piece of paper (plastic, a white file card, etc.) When cleaning, I spray solvent through the air brush and paint cup, wipe it out, spray solvent through it again until it sprays clear, and that's it! Ready for the next time. Ray, believe me, this is worth the investment in money and practice time. Practice on sheet styrene, practice on plastic balls in order to spray on curved surfaces, and get old model shells, too. Once you have the paint pressure, consistency, and technique down, you will never, NEVER regret the money or time, I promise you. You'll ooooh and aaaaah and have something to be proud of every time!
Russ