I would recommend getting a double action airbrush as a-posed to a single action. The difference is a single action you just push down to get the air flowing and you dont have much control of the paint/ink line thickness its just down for air and then move closer or further away from the work to get thinner or thicker lines. With a double action you press down for air then pull back to get the paint flow you want. so when you push down and pull back only a little bit you get less paint but also a smaller line, pull back all the way you get a bigger line and more paint flow.
as was stated before a syphon fed airbrush is more for if you are doing a large area or manny things the same color. I personally have both, i use the syphon fed to do base coats, clears, primers. I then switch to my gravity fed for detail as you can work with a single drop of paint if you want, all the way to enough paint to do a full base coat if need be. Gravity fed is nice also for the fact you use so much less paint you can very easily switch from color to color because your dealing with drops of paint and small areas. I would recommend looking into the iwata neo series air brushes, they are not professional grade but perfect for beginner/ intermediate because they wont break the bank and are still good quality. I personally have both of them and use them almost daily. http://www.amazon.com/NEO-Gravity-Feed- ... 933&sr=8-1
Experiment with different paints, there are so manny out there find what works for you. I personally use createx airbrush paints just because they are so easy to find locally for me. i thin with alcohol or water. I clean my airbrush out with windex or any other cheap window cleaner. CLEAN IT FREQUENTlY DURING AND AFTER USE! THE MORE YOU CLEAN THE LESS WORK YOU WILL HAVE TO DO IN THE LONG RUN! I also fully break down my airbrushes once a month of so and fully clean them.
Air compressor wise there is a ton of options, and i recommend staying away from the "airbrush" compressors. they cost an arm and a leg for a good one and you can get the same performance out of a regular compressor half the price.
I picked this guy up awhile ago, http://www.homedepot.com/Tools-Hardware ... ogId=10053
I added a better regulator, and a water trap. Both parts and all the misc parts I used to make them fit right cost be about 35 bux. I also bought a 5 gallon air tank and added that to it as well so now it is a 7 gallon reservoir I think this was 35 bux also. So for a little over 120 bux I have a 7 gallon compressor, when full i can spray for about an hour or more before the pump kicks back on. Mine is loud but it runs for a few min and then stops so I can live with it. Basically just buy a regular pump and a few misc parts to make the performance better.
I also would recommend buying an inline water trap for the air brush house. It will connect in-between the house and the airbrush its self, and will make sure there is no moisture in the air going threw the brush.
sorry I no its a long post just trying to keep someone from repeating my old mistakes.