Playfelt is right, be calm and relaxed and confident and remember to speak slowly and calmly. Sit down and plan the interview in your mind and how you want the conversation to flow. I had a span of almost 3 years between interviewing so it was brand new again because I had forgotten how to do it but I made myself notes and checked them near the end of the interview to make sure I had covered all the points I thought were most important. Professional confidence is most important.