The basic condition for this is to master and learn the piece thoroughly. It is useful to have an honest dialogue with yourself. Ask yourself questions as often as possible about all this and answer to them and clarify them. For example, ask yourself:
What makes me feel so bad? What can happen to me if I make a mistake? If you analyze all this, you will probably realize how unrealistic performance anxiety is. It is just a product of your imagination and this cognition will mean a lot to you.
When you find yourself in a panic situation you must learn to laugh at yourself. It overcomes performance anxiety. You must learn how to live with it and get along with this problem. Ask yourself a logical question: If everyone has it, isn’t it something normal?
Sometimes you should let this frightening assumption happen to you. What do you think will occur in most cases? Usually nothing, because it is all in your mind and your fear.
Taken from my book