How do you deal with nervousness before a big/important competition?  
Any specific strategies?

Dealing with nerves is a very important part of racing.  Everybody gets nervous,
from little kids to Olympic Champions.  One mistake a lot of people make is to
try to ignore their nerves or pretend that they aren't nervous.  You have to
accept that you are nervous, and then deal with it.  Think about all the hard
work you've done leading up to the race, and how it is going to help you. 
Picture past races you have done well, and try to picture yourself doing well
again.  Try to think as positively as you can, and focus on doing the best race
you can do.  Finally, remember that racing is fun, and you want to do it, even
if it makes you nervous.