Here are some items to consider before you begin the interview:
Good sales people smile; Unless your subject is solemn, begin the taping with a warm smile and friendly appearance. If you are on a talk show, make sure you thank the host for inviting you. Viewers identify with the host or hostess. Share in that image; don't create a distance between you and the host by the appearance of nonchalance or hostility. Keep smiling during the interview.
Look at the interviewer, not at the camera; Maintain eye contact. It enhances credibility and shows that you believe what you are saying.
Repetition works; you've got a message to tell. Start with your most important conclusion. Remember the old adage: tell them... tell them what you told them... then, tell them again. You don't know how the interview will be edited. Keep the focus on your main points.
Remember the KISS (Keep It Simple Silly) Formula; Reporters are asked to cover a wide range of topics. They may or may not be knowledgeable about your subject. It is certain their audience will not know as much about the interview topic as you do. Keep your message simple. Use illustrations to clarify difficult point. Use short, simple words instead of longer, technical terms. Your purpose is to communicate, not to impress.
Plan ahead. Anticipate questions you may be asked. Research answers. Practice answering each question. You can reduce the likelihood of being surprised if you prepare.
Know the difference in NEWS and ADVERTISING; Don't be guilty of over-promoting your organization. It's OK to throw in a plug or two if it is not obvious, but a good editor will cut statements obviously designed to promote the interviewee's organization or position.
Challenge incorrect assumptions. If a reporter makes an incorrect assumption during the interview, challenge the point. Your position depends upon clear understanding by the television audience. They won't understand if the reporter does not understand since it is the reporter who will be communicating your message to the audience.
ENTHUSIASM SELLS! To sell yourself and your message, be enthusiastic.