CONVERSATION
The more reserved attitude of Germans to strangers is reflected in their language. The informal "du" is used for close friends, family and children up to the age of about 16 or 17. The formal "Sie" is used for all other occasions, most importantly in business. Using "du" in the wrong situation can be seen as being precocious.
While polls show that the trend is towards using "du" rather than "Sie" the matter is still a very sticky one. Older Germans clearly prefer the Du/Sie distinction. On the other hand, younger Germans these days are quick to use the informal du, particularly with English-speaking foreigners, since they are well aware that the distinction doesn't exist in the English language.The lines are not so clear cut in business, even if your colleagues have spent a lot of time in English-speaking countries. Promptly using "du" with a colleague who addresses others in the office with "Sie" can make you look brash. However being offered the "du" by a superior is often considered a compliment and hardly refused.
The best way to deal with the matter is to let acquaintances or colleagues offer to use the du form; if you feel comfortable with it. Not so long ago, the offer to switch from Sie to du was done with a small ceremony such as over a meal or bottle of wine since it symbolized opening the relationship up to friendship.
However, using Sie has its advantages, such as in the office: it establishes a strictly professional relationship. As a rule, Germans address others with the salutation Herr, Frau or Dr. (Germans are proud of their academic titles) and not by first names; unless, of course, you are on a "du" relationship with them. At present, a very popular compromise is to address colleagues by their first name, but still use the Sie form such as 'Ingrid, wissen Sie wie spät es ist? " ("Ingrid, do you have the time?") instead of "Frau Schmidt, weißt Du wie spät es ist?"
Identify yourself when making or receiving phone calls. Germans state their names when answering the phone or placing calls. For example: "Schmidt Guten Tag" or just "Schmidt." Making calls after 21:00 is a no-no and doing so upsets Germans.
As they admit themselves, Germans are "direct" or frank. Although shy about extending friendly gestures before they get to know you, Germans are uninhibited in telling you what they think about a matter, such as politics or your appearance. The reason most often stated for this habit is that being truthful is better than being superficially polite. Whatever the pros and cons of that rationale are, be prepared for candid comments. On the other hand, Germans don't have a monopoly on frankness; being candid in return is perfectly acceptable.