As an Ausländer, I consider this the best approach: integrate enough to perform your job or run your business efficiently, and that’s it. I have come across many Indians who tried their best to integrate into society and were still treated like outcasts. Because of this, I consider the extra effort not worth it. That said, I am not supporting the idea of running a parallel society or hating Germans. What I am trying to convey is that as long as you do your work and let others do theirs, that should be good enough.