For your first few interviews, or at least until you are feeling very comfortable, focus your efforts on remaining calm and collected. Do not try too hard. If you have been practicing your responses, you should be able to offer appropriate answers without too much difficulty. Once you begin to feel more confident about interviewing you may wish to think strategically about each interview. One effective tactic is to adjust your speed of speech to match that of the interviewer.
People tend to talk at the speed at which they like to be spoken to.
Another strategy is to adapt your answers to match the type of company for which you are interviewing. When filling professional career positions, few companies will make a job offer after only one interview. Usually, the purpose of the first interview is to narrow down the field of applicants to a small number of very promising candidates. During the first meeting, then, the ideal strategy is to stand out from a large field of competitors in a positive way. The best way to do this is to subtly emphasize one of your key, distinctive strengths as much as possible throughout the interview.