If you’re invited to a dinner and bring wine as a gift for your host, make sure it is Italian or French. Bringing German wine implies you don’t believe the host is going to serve good local wine. At the dinner table, don’t start eating until the host announces guten appétit, which means ‘enjoy your meal’ in English. When you’re done eating, position your knife and fork next to each other. If you cross them, it means you’re not finished with dinner yet.
Besides that, the okay sign (index finger and thumb joined to form a circle) is actually vulgar in Germany, Russia, Argentina and Brazil. In Turkey, it means someone is homosexual whereas in France it just means zero.