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. These paints will have a hard time staying on skin that is oily. 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. Damage to the air cap and head assembly will effect the performance of your airbrush. Make sure that your compressor is rated for the type of work you are going to be doing. In this case it will be airbrushing t-shirts. When doing airbrush art onto t-shirts as a business then invest in a commercial air compressor. It will be worth it in the long run. Most of the times you will need to heat set your paints so that they can be washed without fading or bleeding. Don't just put up pictures of your work though. Make sure to actually talk to your audience. Tell them about yourself and your passion for airbrush art. Show some pictures of your work and tell your audience how you created that design. Talk about the paints that you use, the types of airbrushes and so on and so forth. The other way is that you can freehand the design onto your project without the use of stencils or masks. Most stencils and masks that you purchase are reusable. The stencils are made from different material depending on what the stencil will be used for. But no matter what material your stencils are made from they all have to things in common. Cooped up in a studio too long, then go out to the park and open your eyes to everything that you see. Derive inspiration from various sights around you and incorporate them into one great piece of art. See two kids on a seesaw at the park? Turn those two kids into angels on a seesaw cloud in the sky.