Germany is one of Europe's safest countries. Violent crime affecting tourists is very rare. The standard urban concerns apply: pickpocketing at major train stations (Berlin Hauptbahnhof, Munich central) and in crowded Christmas markets.
Tap water is safe to drink everywhere. Medical facilities are excellent. The emergency number is 112. Germany's transport system is reliable; disturbances are occasionally caused by labor strikes (GDL railway strikes) — check before major journeys.