PSI stands for pounds per square inch and for automotive airbrush art you need a compressor that has a psi of 55-65. Iwata is a great name brand to go with and they offer four compressors that will work for airbrushing automotives. Badger is another good name brand that you can go with. They offer several air compressors that will work when doing airbrush art on automobiles. 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. Using a cheap surfaces airbrush circles, triangles, squares and rectangles. The book explains all about airbrushes and the uses of airbrushes. Instructions are also included in the book on how to use each airbrush. So someone who has no real prior knowledge this book will help you understand the airbrushes that you will be using when creating airbrushed artwork. Getting Started in Airbrush by David Miller is also a great beginner's book on airbrushing. A person with dry skin will get more than 7 days usually from the tattoo. It does not matter though if they have dry or oily skin you should apply talc powder as soon as the airbrush art tattoo dries. Airbrush tattoos do cost money and customers are not going to spend that money if their tattoo does not last for at least close to what is expected. Secondly you are limited to only creating designs based on the stencils that you can get your hands on. While these stencils can greatly aid you in your airbrush art, they also can hinder your creativity. So the best way to deal with having you use stencils and reduce costs as well as leaving your creativity open is to create your own stencils. Remember to do this gently so that you do not break your needle. The better care that you take of your airbrush the longer it will last. So keep your airbrush clean with the right cleaners and once a month do a full break down and cleaning. With needles most artist find that the airbrushes coming out of China bend easier than any of the other airbrushes.