Usually, your stage fright is built upon fear--fear of being inadequate or making a mistake. Often, thoughts of being judged or harshly criticized by the audience add another layer of anxiety. One way to battle this is through building self-confidence.
Give yourself credit where it is due. Don't harp on negative points of view. Address your good qualities and focus on your achievements rather than failures. Acknowledge your capabilities, but know your limitations and work on bettering yourself. Set small goals and praise yourself when you reach them. If you fail at something, try again.
Show self-confidence on the outside, even of you don't feel confident on the inside. Exuding confidence in yourself to others (pretending) has an uncanny way of helping you cope with your fears. You will be more relaxed and your true self-confidence will grow with every successful venture.
The power of positive thinking is immeasurable. Choose a word or phrase that is comforting to you. Or pick a phrase that describes how you want to feel. Whenever you experience, or know you are about to experience, symptoms of stage fright, take a deep breath and begin repeating the phrase over and over to yourself. Focus solely on it for a few minutes. Keep breathing deeply and before you know it, you're more calm and ready to face the music. It helps slow the heart rate and take the focus off of what is causing your stage fright.
It is a good idea to work positive affirmations into your routine. Take time before every performance or speaking event to find a quite place, even if you have to hide in the bathroom, to practice your affirmation exercise. Empower your self with positive thinking.
Embrace your anxiety and fear. Don't work against it; let it work for you. By placing all of your attention on the anxiety you are feeling, you are giving it more power than it deserves. The more you agonize over taking the stage, your agony will only amplify once you're on it. In accepting your fear, you take away its power to control you. Place all of your attention on the task at hand. Whether you are a performer or a speaker, if you focus on yourself on your anxiety, your stage appearance will fall flat and you will be disappointed, thus creating yet more anxiety for the next time you have to take the stage.
Try drinking a cup of chamomile tea about 20 minutes before any engagement or performance. Chamomile has been found to have a calming effect and along with the positive affirmation exercise, you will be calm and ready to focus your attention on-stage.