While there isn't a 'proper' setup, per se, in order to do airbrushing, there's a few things you'd want to take into consideration:
- Your brush(es) and your ability to maintain it/them. Get the right equipment to do so and keep it in good working shape. Not difficult nor time intensive.
- Your air supply almost more important than your brushes. Includes your compressor, regulators, hoses, quick release fittings, etc.
- Your spray area, including how do you deal with overspray, fumes, and what do you spray on. You may consider a booth, fans, etc.
- Your media: what you are going to spray through your brush and how does this compliment your activities in modeling. Having good media can make a difference.
Having the best equipment is not always essential, but it can really make the difference, and make it so you either enjoy what you are doing, or hate it.
As for all these things, there are more cmoplex and expensive ways and there are less expensive ways to deal with things.
Just my 2 cents. No recs, but I could give some later. I've used everything from the cheapest brushes and airsupplies to stuff custom built for airbrushing.