Practice, Practice, Practice. And then Perform, Perform, Perform...This usually results in more practice...
The best advice is simple, as said above, be yourself. Practice some routines. Perform (after you've practiced) until you're comfortable doing so.
Going out in front of strangers is difficult, some people don't want to see magic...at first the reactions may be disheartening...but as long as you continue to work on your presentation and never making mistakes (because a mistake is only a mistake if you fail to learn from it) then you'll get better.
Just remember that books and people can give advice, and you should take it. But you'll find that most people who give advice learned primarily from experience, which is the greatest tool in anyones arsenal.
Hope it was of some help,
Rik