I am starting to do research on the Alexander Technique and performance anxiety. One article I found, lists all of the obstacles that you can face before/during a performance. Some of these may not go away not matter how much you practice, however there are certain ways to reduce the amount of stress of these things.

1. Uncontrollable breathing
2. Tense muscles
3. Loss of balance
4. Unclear thinking
5. Dry mouth
6. Moist hands
7. Impaired sense of time
8. Trembling

Now, I will list a few ways that could improve these stressful things we experience before we do a performance.
1. Breathing exercises, or meditation before a performance can help calm the nerves.
2. Yoga, or brief stretching and deep breathing can help relax the muscles.
3. Practice a few balancing exercises before you go on. (Such as the tree pose)
4. Try to focus on the now, not mistakes you have made or the unknown outcome.
5. Be sure to stay hydrated before the performance.
6. Possibly bring a small rag, or towel to wipe hands before you go on?
7. Relax, to keep away from the tendency of rushing, but be sure to subdivide.
8. Focus on relaxing specific parts of your body before hand. For example for trembling hands, try thinking of relaxing every finger, and possibly even massaging them to reduce the trembling.