Customs of the Country
Being on time for appointments, even casual social ones, is very important. There is no "fashionably late" in Germany. Germans are more formal in addressing each other than Americans. Always address acquaintances as Herr (Mr.) or Frau (Mrs.) plus their last name; do not call them by their first name unless invited to do so. The German language has an informal and formal pronoun for "you": formal is Sie, and informal is du. Even if adults are on a first-name basis with one another, they may still keep to the Sie form.
Germans are less formal when it comes to nudity: a sign that reads "Freikörper" or "FKK" indicates a park or beach that allows nude sunbathing. In almost all saunas or steam baths, you will have to remove all clothing or might be asked to leave.
The standard "Guten Tag" is the way to greet people throughout the country. When you depart, say "Auf Wiedersehen." "Hallo" is also used frequently, as is "Hi" among the younger crowd. A less formal leave-taking is "Tschüss" or "ciao." You will also hear regional differences in greetings.
English is spoken in most hotels, restaurants, airports, museums, and other places of interest. However, English is not widely spoken in East Germany or by people over 70. Learning the basics before going is always a good idea, especially bitte (please) and danke (thank you). Apologizing for your poor German before asking a question in English will make locals feel respected and begins all communication on the right foot.
A phrase book and language-tape set can help get you started.
Under no circumstances use profanity or pejoratives. Germans take these very seriously, and a slip of the tongue can result in expensive criminal and civil penalties. Calling a police officer a "Nazi" or using vulgar finger gestures can cost you up to €10,000 and two years in jail.