just do it. when I joined the army I had a fear of performing. even for friends and family. In time, I started going on guard duty. In hand was a deck of cards. I slowly began to perform nightly for other soldiers. my fear slowly went away. you develop confidence through performing. Just like learning to smoke (which I don't recommend!). to learn to smoke, you have to smoke...
I must say thats a great way of putting it. Everyone chokes on their first cigarette, but if you keep at it it's worth it!!
Im kidding im not recommending smoking. But the point remains. Just keep truckin'. Keep performing for people. Prepare your approach patter and carefully select who you approach. People your own age are definitely the best place to start, because you can relate to them better than any other age group at first.
Most importantly, know who you are as a performer and how you want them to see you. I dont mean, "i want them to see me as really cool and amazing". I mean, are you a card expert? or a character with magic power who uses cards coins and other objects to give examples of his abilities. Do you read minds? or are you a body language and psychology expert. Convey yourself properly, patter becomes easier once you understand your act. Generally for younger performers (excuse my assumption if im wrong) i would recommend performing one trick at a time in the ,dare i say it, david blaine style. If a teenage magician approaches me and says he has studied the human mind and the psychology that drives it, and with that has an uncanny ability to read people, i simply will not believe him. But if derren brown walked up to me, id run for the hills.