TPM has an amazing stat for you. Of New York City's roughy 500 (or less) murders this year, only 35 were committed by strangers. Think about that. Think how we are taught to fear strangers. From infancy we are taught that its people we don't know are the danger, when it turns out that its the people we know that could kill us. Think of all your friends, family and coworkers. If you don't know anyone on that list who wants to kill you, turns out that you are pretty damn safe.
Whole political movements are based around this fear. Here's LG&M knocking down a effort to turn pranks and false alarms into a global terror threat.
Terrorist are not going to kill you. Random strangers are not going to kill you. Just be nice to people you know and you will be safe.