Germany is generally safe. Do look out for pickpockets and purse snatchers, Cologne has a reputation for pickpockets at the markets.
Anything related to the -Nazis regardless photo, relic etc is illegal in Germany. Giving the -Nazi salute is also considered very rude and is illegal. Holocaust denying is also illegal.
There is also the old ball and cup scam found at some tourist centers, where the con man works with a partner posing as a tourist in getting people to guess which cup the ball is under.