Berlin is one of the safest cities on the continent. Of course, just like in any other big city, there are bad areas (they're away from the attractions, so you won't stumble upon them) and the risk of pickpockets around the major attractions, but if you keep your travel smarts with you, you won't have any problems. This doesn't mean you should go unprepared, though. The best way to ease your mind is travel insurance. I use World Nomads for my travels because they have proven themselves to me more than once over the years. If you have another favorite provider, that's ok. Just make sure you have one.