Practice in an Atmosphere Similar to Your Performance
When I was in college, I would set up bright lights in my dorm room (or the brightest I had) and aim them at my practice chair. Then I would turn off all the other lights. Next to the lights I would place a cassette recorder (yes I am old enough to remember when phones could not do this task). Then I'd hit the record button, walk in from behind the chair, take a bow, and practice a performance piece.
I intuitively knew that recreating the atmosphere that I would be in, especially a heightened one, would help my psyche during the real performance. Now that I have more experience and have read much more about this phenomenon, I can say that it is quite remarkable that it actually works.
The same that holds true for the divers also holds true to performing. Whether it is guitar, a speech, or any other situation, you can "trick" your brain into recalling for the event by simulation. It may seem like common sense, but the science above gives evidence of the reality. When our adrenaline is rushing before a performance it can be difficult to calm that anxiety. By already practicing as if you have already been in that moment, you can work to ease the stress that bombards you at that moment.
For me, the ability to record video easily is one of the greatest gifts that technology has given me. It allows for immediate feedback and the heightened sense of performing in front of an audience. The recording listens and doesn't lie! I encourage you to add this type of practice to your routine and you will find that when performances happen the coping mechanisms are much more effective.