What should I wear to the Taylor Swift concert?

I know for my poster, I am bringing a sign that says "It's my 15th birthday!" with lyrics from fifteen on it, because the show I am going to is like two days after my birthday. What should I wear? This is (kinda) my first show seeing her considering I couldn't get tickets for the Fearless tour, and the only other time I saw her was waaaaayyyy back at the Christmas Tree lighting in New York City and I wasn't even that close. What do you think I should wear?