An interview is an opportunity for you to demonstrate what you are made of.
The anxiety we tend to feel is due to the fear of the unknown. Try to think of fear standing for: False Expectations Appearing Real.
You are unique. No one looks like you, thinks like you or has your personality.
Accentuate the positive but be able to handle questions about your weaknesses. Think about your experience and what you could bring to the job.
Be prepared; know your stuff, do your research about the company and practice answers to difficult questions. (There are plenty of books to help you with this.)
This will engender confidence. Arrive early. Offer a good, firm handshake at the introduction and maintain eye contact throughout the interview.
Good questions will impress the interviewer. Support your answers with examples and points you want to make.
Breathe deeply, smile, and try to relax. Focus positively and feel confident. You can overcome the fear.