Below is a link to an article I wrote a couple of months ago (for DIVE Magazine, which is now online) on how to succeed in UW Photo contests. It is written for the upcoming BUIF comp, but it is most generic for most competitions.
I feel as if I am in quite an unusual position at the moment, as I sit on both sides of the fence. I judge a lot of major competitions each year, but unlike nearly all the folks I judge with, I also still enter photo competitions (obviously not the same ones - that would be too easy). I tried to write the article from both perspectives.
http://www.divemagazine.co.uk/news/article.asp?uan=5475
It is not a complete list and I know that we have discussed entering competitions on Wetpixel before, but I thought it would be good to start a fresh discussion. So any other tips great
Alex