Dealing with "high profile" clients

I am currently expanding my work and doing more freelance work on the side. But I don’t have much experiance in dealing with clients.

I recieved an email from a popular underground rapper that was along the lines of “im definatley intrested…lets build”

I wasn’t sure how I should approach this, should I be marketing myself or just request what he needs done?

Also,
Are there any good books on this topic in the design field?

btw Im fully capable of doing the design work and handling a large project, but the business side wasnt normally handled by me. (im also going into business at school)