You could practice online.
http://www.overthewire.org/wargames/
You could read some good books.
http://www.gaiaonline.com/forum/c-t-tech-talk/suggested-reading-technology-and-programming/t.69647195_1/
You could take a class.
http://daeken.com/2013-06-11.1_Breaker_101__An_intensive_online_web_security_course.html
Or you could go to security conferences and practice at CTFs. (Some conferences allow you to participate remotely.)
You could find a local Hackerspace. Some have CTF teams.
http://hackerspaces.org/wiki/
You should learn a programming language (or several).
http://sitwon.github.io/learnproglang/Home.html
Take up locksport.
http://toool.us/
And remember, even though it's a competition and it can be fun to win, winning isn't everything. Take your time, be thorough, and focus on learning as much as possible. Not on being the fastest. When you rush, you'll miss things; and this is a game that is all about the small details. You want your team to be calm but persistent, not frenzied or panicked. Remember, focus on learning as much as you can. If you do that, you'll win even if you don't place first.