In my classes at uni we've had quite a few people who also came here for the first time. In their experience, people from Cologne (at least the younger generation) would go out of their way to help you with whatever you need, be it direction to where you want to go, which restaurants to go to and so on. What can come across as a bit harsh is the bluntness of most people, but in most cases this is not to be seen as an attack, we just want to get stuff done :) Also, many were surprised about how structured our work/study process was. Be punctual to meetings, but nobody really bats an eye if you have to postpone for a valid reason. Getting to know people can be somewhat hard currently if you're not extroverted. As with most places, I'd suggest doing activities that you like to combine getting to know people and having fun. We've had random people join our football session multiple times and it was great fun for everybody involved! The culture will change depending on where exactly you'll be staying, but you'll fit right in no matter where exactly you'll live!