My friend who does this gets paid in cash by the photographer for the session.  The photographer then sells the photo's or video to the highest bidder.  One session ended up being used in a magazine that she ended up being cover-girl for.  She didn't get paid anything extra by the magazine though.

I suggest you contact World Modeling Agency in Sherman Oaks, CA at (818) 986-4316.  World Modeling handles about 90% of the porn actresses for both still photography and videos.  Tell them what you are planning on doing:  They will explain the best way to go.  Tell them that Ace referred you.  Good luck on your new endeavor.

http://www.sexyjobs.com/main.asp

while WMA is a good and rapid way to fall & tumble into the biz head first, it's also an agency that will "eat you up" if you're not familiar with the bizness. my advice would be to practice your "chops" with smaller agencies before going in for the "kill" for WMA. there's plenty of stories of use and abuse of models by WMA and folks they do business with

don't ask me how i know!  

I just worked with Scoreland and I dealt with them directly. I worked out my terms and fee and we both had lawyers go over it before we signed. Agencies (except World Wide) are a waste of time and take a % of your fee for modeling as are photographers. They pay you a flat fee and then can sell your image to whom ever they want and you get nothing! If I had worked with a photographer directly he could of sold my pics to  "Juggs" "Big Butt" "DCup" and made all the $$$$$ for himself. Screw that! I know am working directly with each magazine or website so I make all the $$$$ I can and spell out my terms of what I want. Don't be fooled with this "I'll make you a star kid" it is BS. Hope this has helped,DevinDDD Taylor
PS Shameless plug for me ONLY if you like big chicks: Cover girl for Sept's issue of" XL Girls" and a layout in Sept's "Voluptous"