Twitter Contests and Twitter Parties are a relatively new concept, and very easy to win. The great thing I love about most contests and twitter parties is that your odds are based of your effort with the contest, and not just random odds.
Since this is a relatively new platform for contests, your odds are much better than you would think. I have won some really great swag from Twitter including a Rubik's Touch Cube, and a pair of Muk Luk Boots to name a few.
The important thing is to pay attention to the rules. Some contests allow you to Re-tweet a message as many times as you would like, others have restrictions for one Re-Tweet per hour. Reading the instructions will help your odds and save you time.
My last tip for Winning on Twitter includes finding others that love to win prizes and follow them. It's a great way to find new contests, and make friends (tweeps).
Want to follow me on twitter, search for @JCausby.