Filmmaking / Directing : Indie music rights and negotiations by Simon King

I am working on a new series and we have strong interest from an unsigned UK band/artist to use her song during the title track/ending credits sequence. Our budget sucks and she knows that. There is solid value for the production to use her music and she welcomes the opportunity to grow her market in the US teen audience. Any thoughts/comments/experience on working on this sort of arrangement? Examples of agreements? The good, the bad, and the "Oh Crap!" of licensing from an unsigned musician?