Buy your self a airbrush set with compressor so that you can get an idea if it is a medium you wish to get into. Some aritist use paint brushes others use the airbrush sets you will need to know how to use stencils. Depending on the style of art work you wish to use on your model. Before paying big money to use a model to start with try working with models that will do tfp and you can paint body parts when your ready for a full body paint you will be set to go. I am sure you will get some replies from other painters in here ask them to give you websites that sell latex paint for body painting. Good luck
Makeup Forever offers body painting classes at their school. Also, check up on Makeup Forever's classes they offer at their boutique on 12th...they have a variety of lessons every week and I've taken a body painting class there before. I think the cost is $90, redeemable in product.
It would be worth looking at your favorite body painters and asking if they are doing any teaching tours soon, many artists such as the Wolfe Brother, Vargas, Emma Hack, Lynn Jamison tour worldwide often.