Samantha; I pretty much agree with owendancer, start with the dances that you will use the most. East coast swing is danced at most ballroom dances, even the formal ones around here, plus there are clubs that have dances for this. It's a fairly easy dance to learn too. Hustle isn't as common in ballroom venues but you'll find it's popular in clubs, particularly with younger groups, and another that is easy to learn. If you like latin music, think about Mambo/Salsa, they are nearly the same dance. You'll find ballroom people doing Mambo and clubs favoring Salsa, but when it's "Salsa on 2" I don't even know what the difference is. West coast swing is another popular club dance, but you won't see it much in ballroom venues and it's a more difficult dance to start with. I really enjoy it but I think some of the others might be a better place to start. I live in Ohio, you might want to look around a bit, different dances are popular in different areas.
Good luck, whatever you pick, I'm sure you'll be glad you started dancing.
Gary