Anything really! There's many places you can go and so many people to meet! You'll see cosplayers from any anime or video game, etc. Everyone loves everyone so be yourself and don't be afraid to talk to people. I definitely recommend going to the dealers room so you can buy some awesome things or knick nacks. Here's a video from Anime Detour 2013 that you can look at if your still curious of what to expect!
https://www.youtube.com/watch?v=kXjMOzKREPg
