"Oh, my goodness. I could never interview someone!" Is this what you say?
As a writer of nonfiction, you're going to have to get over these inhibitions. Can you talk with people easily? Then, score one in your favor. Some people say conducting interviews is just like having a conversation. Unfortunately, that's not quite true. Conversation is back and forth dialog with shared emphasis on each person. That's not how interviews are done.
An interview puts all the focus on the person being interviewed. The interviewee could care less (usually) about your thoughts on such and such or your related experiences. You aren't there to make life-long friends with the interviewee.
Your role is to get information. To do that, you need to make the interviewee comfortable enough with you as a person so that he or she provides valid answers.
What if you have no experience in interviewing someone? Fake it. You will set your interviewee far more at ease if you display confidence in what you are doing. If you act nervous and hesitant and apologetic, you will make the other person ill at ease which results in rarely getting all the information you want.
There are several things you can do to exude confidence while getting an interview (even if your knees are shaking underneath your slacks):
1. Start asking questions of friends or family members as if you are in an interview. If they ask why you seem different than usual, tell them you are practicing your interview skills.
2. Practice your listening skills. If you aren't a good listener, you'll have to become one.
3. Watch various commentators or hosts on news and talk shows---preferably good talk shows. Look for things that work well that the interviewer does. Find one or two journalists who you especially think do a good job. Study their techniques when asking questions and listening for answers.
4. Until you develop the needed confidence, it often helps to keep an image in your mind of a journalist whom you admire as you begin your interviews. This reminds you of the positive attributes you noticed and wanted to embed into your own abilities. Once you become comfortable with your own interviewing techniques, you won't need to keep imaging some other journalist. You'll have developed your own style.
5. Know as much as you can about your subject before you get to the interview. You don't want to be asking questions for which answers can be found in the first paragraph of every article about the person or subject.
6. Have your list of questions written ahead of time and take them with you. The order in which you ask depends on the person and subject being interviewed.
7. For an in-person interview, phone or email the subject to set an arranged time and place for the interview. If your own schedule is not 100% flexible, suggest three or four dates for the subject to select from. However, you are the one who should make yourself the most flexible. Explain briefly in your call or email who you are and why you want the interview.
8. Phone interviews are set up the same pre-arranged way as in-person interviews. However, you must be prepared in case the subject says, "What about now?"
9. Try to arrange for the interview in a quiet place free of distractions.
10. Keep things moving. Don't dawdle. Be respectful of the interviewee's time.
If you are completely new to interviewing, it's not advisable to interview the most famous person imaginable until you get comfortable with your skills. Yet, if you feel the urge and this famous person is in the realm that you could get an interview, go for it. Nothing is impossible. Nevertheless, starting out with people you feel are less intimidating helps you build confidence. Fawning over the subject you are interviewing establishes you as an amateur and you won't get the quality of interview you hoped for.
Practice to build confidence, but while you are practicing, remember, fake it. Faking the confidence you need, helps it become a reality. The person you are interviewing may never realize this is your very first interview.