The gravity feed is a top mount cup that uses gravity to pull the paint down into the airbrush. This feed is great for airbrush art designs that call for fine detail as the gravity feed uses less air pressure. The less air pressure means that you can use slower movements when airbrushing. The bottom feed is where the cup is mounted to the bottom of the airbrush and the paint is brought up via a siphon tube. Practice spraying the airbrush at your cheap surface while you learn just what pressure is needed where. If you are using a double action airbrush you should be experimenting to see how far back gives you how much paint spray. Once you are comfortable using the airbrush then you should work on creating shapes with your airbrush. In a dual action airbrush the trigger controls both the air flow and the paint flow. Beginners should really take the time to practice on how the trigger works so that they can perfect their ability to airbrush. Your airbrush will have a back lever as well that acts to shut off the air flow and paint flow when the trigger is released. When using automotive paint make sure that it is thin enough to flow through the airbrush. If the automotive paint that you have chosen does not flow then thin it down so that it flows. The paint should be thinned to about a milk thickness. A good automotive lacquer will work fine to thin down your automotive paint. With needles most artist find that the airbrushes coming out of China bend easier than any of the other airbrushes. So look for one that is made elsewhere so that you do not have to keep trying to straighten a bend airbrush. The best airbrushes to use that are the easiest to take care of are name brand airbrushes. While an experienced airbrush artist may know this a beginner may not, so it is worth mentioning. When doing airbrush art on skin make sure you are using airbrush paint that is designed for the skin. Usually this will be sold as airbrush body paint or airbrush temporary tattoo ink. These are the only types of airbrush paints that are safe to use on the human skin.