1) Don't walk in the bike lane. You will get your ass clipped off. Berlin is a cyclist's dream city. There are built in bike lanes next to every sidewalk. They come complete with their own stoplights. It is very easy to find yourself wandering in the bike lane if you are not familiar with the layout, so stay in your pedestrian lane.
2) Every dude has "The Macklemore" Not sure when this haircut became so popular but 9 out of 10 dudes have it here.
3) Nobody takes cards. Carry cash with you everywhere you go.
4) You can drink beers in public. That results in lots of broken glass on the street. Watch out if you are in your flippy floppys.
5) It's a nice city. Apartments can be big and beautiful and not that expensive. Great place to edit/work/whatever it is you do.