Give away something!
People like getting free stuff, but you can't count on many people finding your contest. Pick something small to start, like a 1 month gold card for Xbox live. Ask people to write a review, and then pick a random one as the winner. You can't expect people to just randomly find your contest, so you will have to post your contest on several other websites and tell everyone you know. It would be good to find a few blogs with a modest amount of readers to post about your contest.
1. Constant updates - makes regulars check more.
2. Advertise - brings in fresh blood.