I airbrush stencils on custom t-shirts, sweatshirts, and jackets for friends and family. I have had excellent results with
Jaquard Textile paints for light colored fabric and
Jaquard Lumiere for metalics and darker fabric. Not very expensive and both are for painting, stamping, stenciling, airbrushing on natural and synthetic fabrics. Thin with water, soap and water cleanup. I buy red, yellow, blue, black, and white and mix my own tints. They need to be heat set (I use an iron) and have had excellent durability (the fabric wears out before the colors do.)

Not a great picture (both textile and lumiere,) but you get the idea...