The only requirement for the paint you use is that it has to be thin enough to pass through the airbrush without clogging it. You can thin many paints and inks with the proper thinning agent.  Any art store will sell airbrush paints, pre-mixed and ready to put in the cup. That’s by far the easiest method. The beauty of airbrushes is their versatility. People use airbrushes for spraying everything from cake decorating to fine artwork. Airbrushes are also commonly used in painting models and nail art. All of these activities would require a different type of paint. By far, the easiest pigments to use are water-based paints. Having unlimited and free access to the paint solvent and cleaner comes in very handy. Plus, most water-based paints are safer than the alternatives.