I'm an American student studying abroad next year. Any advice on how to fit in?

I'm going to be studying in Vienna and I'm really excited! I want to look like I belong there, though. For anyone in Europe, do you have any advice for how to dress, act, etc? What are common mistakes you see Americans making? Most importantly, any tips on how to fit in socially (I'm trying to learn some German, because I don't want to be that obnoxious American that expects people to cater to me)? Thanks for any help you can give me!