I found this article today that I thought was worth a mention..

http://digital-photography-school.com/blog/how-to-win-a-photography-competition/

The basic tips in summery:

1. Know and Follow the Competition Rules

2. Stick to the Theme of the Competition

3. Do Some Research

4. Avoid Cliches and Stand Out

5. Aim for Technical Brilliance

6. Avoid Distracting Elements

7. Go for a Reaction

8. Enter Another Competition

Tongue in cheek, but true - one comment mentions:

Gary Anthes Says:

My advice if your contest is being judged by an avant garde photographer, a museum curator for example:
1. Throw away all your nature photos.
2. Throw away most of your color photos as well as anything that looks like it might have been taken on a vacation.
3. Forget everything you know about keeping your camera straight, keeping things in focus and proper exposure.
4. Go out and photograph some old people, the more wrinkled the better. Extra credit for tattoos and missing teeth.
5. Or, photograph people who are obviously poor or homeless. Extra credit for tattoos or any evidence of substance abuse.
6. Failing 4. and 5., find anything that most people would consider ugly. Could be trash in an alley, road signs and telephone poles, graffiti, etc. Black and white only, please.
7. Don’t worry that many of the other winners will have similar stuff. You are now a winner, and part of the avant-garde!

Guess I better start deleting some pictures..