It is important to keep your needle from getting bend and either straightening the needle or replacing the needle. The air cap and head assembly are on the front of your airbrush and they cover the tip of the needle. The purpose of these parts is to control atomization of the paint spray. Should these parts become dented or damaged in anyway you should replace them immediately. One way is all the design to fully dry then place a cloth over it and iron the shirt with the cloth between the t-shirt and the iron. Always keep the iron moving though so that you do not burn the material. Another great way if you are doing this at home is to allow the design to dry then turn the shirt inside out and throw it into the dryer for about 40 to 45 minutes on the highest heat setting. 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. In this case you are still going to use the alcohol but for airbrush tattoos it is to get rid of the oil on the skin and not to sanitize an area for a needle. Once you have removed the oil from the area the airbrush art tattoo will stick a lot better. This will give more life to the tattoo. Now that you are ready to begin airbrushing the tattoo on, you need to take your time and be careful of what you are doing. No matter what material you go with make sure that you remember to cut out your areas slowly. By taking your time you can make sure that everything matches up the way it should. If you are doing a stencil for say a dog then you would want to take your time and make sure that the eyes were the same size, the nostrils were cut out shaped the way they should be and so on. If you don't want to get outdoors to look at new scenery and you don't want to go to the library then you can just surf the web. The internet if full of inspiration for your airbrush art. Start looking at various images and keep surfing until you find the one that gets your creative juices flowing again.