Classical musicians that I've talked to recently say that the older they get, the more difficult it is to handle their nerves on stage.
Why is that the case? Is it due to the lack of performance opportunities or the amount of pressure that we put on ourselves when we perform in front of an audience?
It may be a combination of both.
That's why it's important to know your tendencies and learn how to control them.
Each performer has their pre-concert rituals that help ease their sweaty palms and twitchy fingers. But there will be a performance where you won't have the luxury of your pre-concert ritual.
What will you do then?
What it comes down to is the amount of time you practice and perform. We're so concerned as musicians to get everything perfect in the practice room that we forget that we actually need to get comfortable performing in front of people.
If you're a conservatory student, then one of your options is to play in front of your colleagues in a studio class. Or, maybe you practice performing behind closed doors and you perform for your friends. You have the control of the venue. it doesn't have to be anything fancy!
The only way you get better at it is by doing it more. It's also important to know that you shouldn't be thinking about perfection. You should focus on playing your absolute best in different settings.
Performing doesn't need to be scary. Performing more gets you out of your shell and will help you improve on the bigger goal: sharing music with others.