Although I've come across some insightful replies on this thread, regarding overcoming stage fright ,I'd still say it's unavoidable and painful at the beginning.
The stage environment is so unnatural for anyone.
I did find that doing it often, very often, one starts to identify as a songwriter/performer.
When this happens it's a good thing, then you can start really concentrating on what you're doing.
Only then do you have a fair chance.
It doesn't help much, does it? Lol.