Some good info in this thread! I would echo the suggestion that it's a good idea to pick one or two breeds and focus on them, if you try to scatter your efforts too widely, you won't be as successful as if you focus.
The other thing I will add, is that it's a good idea to join the breed clubs of the breeds you're deciding to focus on, as well as to join the American Bantam Association and/or the American Poultry Association, which are the two groups which sanction shows.
Poultry Press is the must-have monthly newspaper for the show fancy. Well worth the subscription.
Also, if there is a local poultry club near you, by all means join and network with other breeders. You will find them to be helpful and (for the most part) more than willing to assist you in learning the ropes. If the club has a show, offer to pitch in to help set up and tear down, or do other volunteer work. Showing your birds is more than just showing up, it's a real community of people, some of the nicest you'll meet! Chicken show people are just the best, really.
I have put together some good info for newcomers to the show scene here, see these links for articles about prepping for show (bear in mind, you need to get started many weeks before the show date! Good condition starts months before a show):
http://www.pathfindersfarm.com/Articles.html
And if you have any questions, please don't hesitate to ask me either here or in email, I'm happy to help!
Cheers,