I'd jot down what you hope to get out of the experience now while it's fresh in your mind, and remind yourself every now and then. I did a stint in Berlin, it's a great city. Best part of living in a large city is the variety of people and the interesting things they're doing. It's great to scope out the city and see what's happening, try new things but the sooner you find your people and get going on what exactly you wanted to do to further yourself professionally the better! It's definitely very easy to get distracted in Berlin :-)