I tend to use a lot of garlic, and some parsley for colour. Only recently did I try it with cumin-- what a difference! Adding red pepper would be extra tasty if you added another kind of beans too, like black or pinto. Yum!
Hmm, now I'm curious to try a garlic/basil/parsley/oregano combination with some sundried tomatoes...
The Sophia Loren tutorial is excellent, definitely try that. Something that I've found very helpful is to print the image on freezer paper (you can find it at a grocery store near waxed paper-- similar, but not the same thing). Print on the unwaxed side, then cut out the image with an exacto knife. You can iron the stencil directly onto fabric so it won't shift at all while you're painting/spraying/whatever. It works really well. =)
Fabric paint (like the kind that comes in bottles/tubes) is permanent and washes okay. I use it for stencils-- partially because it works really well, and partially because I can't find acrylic textile medium except online.