When I read Backroom to the Concert hall I was thinking about something else for a moment
Who cares if I make a mistake, I dont care, no one else will care, no one will remember it in time to come, so there is nothing to lose.
Throughout my life I have watched music competitions and performances and have seen people botch it up all the time. But can I remember it? Do I remember their names? Do I think about their mistakes when I go home and for years on end? I have a lot more important things to dwell on and so do many people.
YOU might dwell on mistakes, I know I did for big stuff ups I have done in the past, but no one really cares, or gives a hoot. If I spent $40 for a ticket to your solo concert and you trip over yourself throughout the program it is a different story, but if I don't have to pay to listen to you what have I got to complain about?
Mental preparation is one thing but you can prove to yoruself through example that you can play without problems in front of people. I will set up recording instruments and imagine that they are an audience, I will force myself to feel the pressure that I cannot stop the recording if I make a mistake (just like in a real peformance). Play through what I need to play, and observe the results at the end.
If I have a big public event then I will do this countless times and hours weeks before the event every day. It will be almost an obsession to prove to myself that I can do this with 99.99% satisfaction. I also make sure I know how to recover from positions when I make mistakes, so through practice I might force an error and try to bring the music back, this just gives you more experience recovering from errors, so you don't do the dreaded STOP IN THE MIDDLE OF THE MUSIC AND FORGET WHAT TO DO what to do mistake.
Do many smaller private concerts as a warm up. Whether that be in a retirement villiage, church, school, univeristy, etc.
When we do things we feel uncomfortable about this is where we grow the most in life. If we go through life comfortable and easy then we will die very disatisfied with our lives. TAKE RISKS!!! My favorite quote: The greatest risk in life is to take no risk at all!