Demonstrate enthusiasm, interest and confidence. Use positive words to describe your skills. Be prepared with specific examples of how you've demonstrated your skills. Listen effectively, paraphrase to clarify and confirm the interviewers question and answer what is asked. Make an effort to talk more deliberately and articulately then usual.
Most people tend to speed up their speech when they're nervous.
Follow Up As soon as possible after your interview, you should send a letter of thanks to all the people you met and talked with that day. While it may not affect the probability of getting a job offer, it is a common courtesy and just may make the difference. The letter provides one last opportunity to stand out among your competition. At the conclusion of the interview, you should find out how long you can expect to wait regarding an employment decision, and feel free to contact the company to check on delays if you don't hear within a few days after the estimated time. Don't be afraid to turn down a job offer if, after careful consideration, you feel it is not the right step for your career goals.