Volkers Link "Peach-Coconut-Modell" fand ich sehr interessant und treffend.
Hier nochmal was über cultural differences: "about friendliness and respect"
Germans and Americans have a few different standards regarding what constitutes "politeness". Americans tend to define politeness in terms of "friendliness": smiling, telling "white lies" to avoid hurting people's feelings, pretending to like people even if we don't, saying "Hi, how are you?" whether we really care how they are or not, etc. Germans, however, tend to consider "respect" to be the proper way to show "politeness", and "respect" assumes that the other person wants an honest answer, not some pretty little "white lie". So, if you're really wanting your ego stroked, DON'T ask him, "So, how d'you like my new dress?" You might not like the answer that he gives. Likewise, DON'T EVER say anything to him "just to be nice" if you don't really mean it; he is too likely to take you quite literally at your word and then be terribly hurt later when he finds out that you didn't really mean it.
Direct questions rarely offend Germans (assuming the question isn't too personal), and they're typically more than willing to give straight-forward answers.
Don't try to make too much "chit chat" or "small talk" with him. Most Germans know little or nothing of the art of talking about banal, superficial topics as a way of "breaking the ice" with new acquaintances; that custom belongs to American-style "friendliness" and is not part of German "respect". Germans also often react negatively to the shallow, superficial quality of casual friendships/acquaintanceships in the U.S., and so he might react negatively towards you if you engage in much "light" conversation.
If you're looking for good topics for conversation, try: politics, current events, philosophy, or any subject he's studying in school.
Don't be afraid to voice opinions that might be different from his; if your opinion is at least logical, well-reasoned, and well-informed, he will more likely respect you for having your own mind, rather than be offended by you for having a different opinion.
And if you don’t know much about international politics, news, current events, foreign cultures, etc., then LEARN! FAST! Americans have an international reputation for being extremely ignorant about the rest of the world -- because most Americans are ignorant! Germans, however, usually are not!