Try to smile while you are talking and see how it improves the way you look. This is the time to let your enthusiasm show. One of the most attractive attributes in a job candidate is a genuine interest in the work. Do not worry about your nerves - just concentrate on enjoying the interview. You are well prepared and confident that you are the right candidate for the job, and you can look forward to meet the employer and telling him or her about yourself.
Breathing exercises are one way of managing feelings of nervousness.
When we are under strain our breathing is likely to become shallow, and we do not use all our lung capacity. The effect is to starve the brain of the vital oxygen it needs in order to think quickly and clearly. Just before you enter the interview room, take several deep breaths. This exercise is easiest to do when standing. Inhale slowly, breathing through your nose, and try to fill your lungs completely.