In a few basic words Strive for excellence, not perfection in the interview .
Your attitude is central to assessing your ability to do the best that you can do.
And that’s all you can do.
If you set a goal for yourself, number one get the best coaching that is available. Number two practice the right concepts and give it all you have. At that point there is nothing more that you can do. You have done the best that you can humanly do, so there is no more reasons to stress out and become nervous.