i use a paasche single action siphon feed airbrush with an h-5 tip. this tip allows for good coverage at a higher volume making the job go alot quicker then the h-3. i use the folk art metallic and apple barrel acrylics. have not bothered using the more expensive model masters acrylic as the cheaper ones have worked just fine.
i have tried, by recommendation, windex or alcohol to dilute and didn't like it. it made a clumpy mess of everything. i have found that about 60/40 acrylic paint to warmed distilled water is the best to dilute the paint and not cause any clumping and gives the most consistent coverage.
+1 on the frog tape, although i have used the painters blue tape with good results.
prepping the surface with at least rubbing alcohol and a cotton swab to get all of the oils off that may have been transferred from your fingers while building is good. then if you are using tape, go ahead and scuff it with 120 grit sandpaper so the paint will stick better.
i never primed with airbrushing. did not find a need to.
only other advise i can give is paint the lightest color first to darkest color last. it may take 2-3 coats to get it nice and deep. airbrushing makes the best use of the paint without using to much compared to brushing with a brush.
here is my latest airbrushing. the first one is to show the difference with airbrush (red) and foam brush (black)
Nothing said I had to crash