I'm a graphic artist digital and print/front-end designer and developer. Recently I was approached by a friend to design cover art for his book. He had informed me he couldn't offer me a payment but would offer credit towards my work within his book.
I don't mind doing the work as a favor however I wanted to ask for royalties on books sold. As I am new to licensing artwork i'm not sure what to charge for royalties or what steps I need to take to protect my artwork. Any advice or information on how to proceed within this dilemma would be greatly appreciated.