Thinking about the consequences of failure, ignoring your feelings and engaging in detailed planning don't sound as fun as advice like "Follow your passion!" or "Stay positive!" But they have the decided advantage of actually being effective -- which, as it happens, is exactly what you'll be if you use them.
Being put on the spot to display one's knowledge or skills can feel terribly uncomfortable and scary. The key to overcoming these emotions is to be prepared and recognize that our fears stem, not from a lack of self-worth, but quite the opposite. Our fears are born out of a deep sense of love for the self that wants nothing more than to protect us and keep us safe.