Doing an interview is not difficult, actually, it's quite fun. First of all, contact the person you'd like to interview telling them about what they will get from the interview. One of their benefits is more fans, since you're sharing the interview with your own list. Another one is a new material they can post on their own site, and even more authority, since they are getting interviewed. Next, send them some key points you'd like to discuss with them. I usually send them five questions that I think would help my audience.
For example, if you could do one thing to become more productive, what would that be? Or what was one of the challenges you encountered while you've tried doing that? And how did you overcome it? Or can you give the audience a next step after watching this interview? All right. Now, record the interview.
Make them tell stories. And talk about their own experiences. This is what most audiences are interested in.