Do not address people you do not know, especially older people, in the familiar "du" and do not use their first names. It is "Sie" and the formal Herr/Frau + surname for anyone older, in a professional setting such as government offices, etc.
--Rikki
80
Do not be shocked when Germans start talkint to you in English right as they see you. Germans like practicing their English whenever they have the chance, so if they realize you aren't fluent in Deutsch, they will switch to English. As they say, "If you want to learn German don't go to Germany"
--Cocoo
