An article from NPR on performance anxiety has some excellent quotes from Californian pianist Sara Solovitch:
“You have to practice performing as much as you practice practice.”
Take every opportunity to create a performance environment – ask family to be your audience – or record yourself.
“Now as I approach a performance, instead of saying ‘I’m nervous,’ I say to myself ‘I’m excited.’ ”
Train the voice in your head to help rather than hinder you.