Some practical tips:
As the performance approaches, take a sip of water, 3 deep breaths and shrug your shoulders. Why? If your brain does not get oxygen you will not perform at your highest level of potential. Quite often we tighten our shoulders slowing the blood supply (carrying oxygen) to the brain and we take shallow breaths.
One mistake does not a failure make!
Immediately move ahead in your thinking. Stewing about it will jeopardize the rest of the performance and you may very well have an unnecessary disaster because you didn't discipline your mind. It takes a decided act of the will at that point to move on, but this provides you with the opportunity to finish well. In fact, a performer may well finish better than ever because he/she is determined to put that slip up out of the minds of the listener.
1. Utilize all levels of memory
Visual - the way it looks on the page
Aural - the way you remember it sounds
Kinesthetic - your fingers "know" where to go
Analytical - the analysis, done at the lesson
2. Plan "jump ahead" spots, i.e., places you can move ahead to, should you encounter a memory lapse.
3. Practice having a memory lapse and jumping ahead to your "jump ahead" spots.
4. Play memorized pieces for
Yourself 4 weeks before performance time
For family 3-4 weeks before
For teacher at the lesson beginning 3 weeks before
For other students and friends 1-2 weeks before