Most of the places you travel are pretty much safe, but there are always some exceptions. Let me tell you a quick story about a girl who stayed in the same hostel as me in Seam Reap, Cambodia.
She was robbed twice on the same day. In the morning, she went for a walk to discover the city, and some guy on a moped stole her golden chain. Later in the day, she was robbed a second time by another guy in a snatch-and-grab attack.