Eat a couple of bananas. The day of. Not kidding.
Never heard of bananas for anxiety...I'll test it out to see if it works.
Although, I've pretty much conquered the stage jitters I used to have
Smoke weed right before the show.
Probably not the best choice, unless you want to play "Big Balls" all night. I've known a few players who can function perfectly while baked, and I have no idea how they can do it. It destroys me!
To deal with nerves in the past, I would start a gig with a beer or small shot of whiskey, bourbon or rye. Now I just grab a beer because I like beer! But of course, yours is not a bar gig, so that wouldn't fly. I don't recommend using alcohol as a crutch. It's not wise and you'll get trapped in a bad cycle and eventually need it to get on stage.
It's true - repeated exposure lessens your nervousness. Eventually you'll be right at home being the center of attention and won't get rattled at all.
Stage anxiety produces a real physiological reaction with embarrassment, accelerated heart rate and blood pressure...and consequently your brain goes into a mild "fight or flight" panic. It's tough to think clearly when all of these vital signs are going wacko.
The best thing for me was to keep in mind that I'm the best freakin' bass player these people have ever heard...and they're going to be amazed at the simplest trick in my toolbox.
99% of the audience will not notice a missed note don't sweat it
Yep, and the audience is not on stage for a reason: they don't know music like I do, and I can count on the fact that most of it goes over their heads anyway. I'm not trying to be cocky, but it's predominantly true, and it's how I approach performance.
Keeping all this in mind, if I make a mistake now, it's very momentary and the recovery is fast. Only the die-hard musicians in the audience (which are very few) ever detect any mistakes. And, all my musician friends totally understand the nature of making mistakes, so it doesn't bother me to screw up in front of them!
As for that, I was a performing artist (acting and music) for many years when I was a young man and never got over stage fright. The only way I could find to cope was just to go through it and do it anyway. As others have said, repeated exposure will lessen the nerves - it builds confidence and increases the familiarity of the performance environment. There aren't many mental tricks that really work and I don't recommend beer (I used that a few times when I was an actor).
Yep, just get up there and do it.
Each time you step off the stage a changed person.
Eventually, you'll have no problems whatsoever.