I used to have panic attacks. I found this book to be immensely helpful:
Amazon.com: The Panic Attack Recovery Book: Step-by-Step Techniques to Reduce Anxiety and Change Your Life-Natural, Drug-Free, Fast Results: Shirley Swede, Seymour Jaffe: Books
It's very practical, and really gives you the tools you need to deal with anxiety. You definitely need to figure out what's triggering yours, but don't make the mistake of associating certain places where you've had the attacks with the attacks themselves--that kind of stuff causes a secondary reaction, and then you find yourself feeling like you don't have any control over them. Just remind yourself that it's just a panic attack, you won't die from it or anything, and concentrate on getting the focus outside yourself and breathing slowly. The book is a good all-around tool to help you re-direct the way you deal with stress.
Xanax helped a lot, too.