Learn some German

First rule to survive in Germany: be able to speak German!
It might sound excessive, but it really is not. It is true that the breaking majority of Germans do speak English, but sooner or later you will get stuck and regret you didn't take that German crash course some blog strongly recommended.
At the university all the lessons are in German, and the subjects are hard enough per se, so that there is really no need to spice it up with a language handicap. At the beginning, it was sadly a usual thing that we got out of a lesson without even having understood the subject they were talking about.
Besides, you will be much faster than expected asked to write reports...in German. And then again you'll be stuck. That will either make you want to carry on, learn quick and catch the train, or just pretend you are doing quite well with your English until you wake up some day in a room with other 3 students, subject to an oral exam, to which you have to answer in that language you decided to bry deeply underground.
You don't want to live such frustrating experiences!! so plug in your batteries and "know kung-fu".