One of the greatest things one can do to protect themselves is to be aware. Being aware means not getting lost in a song's lyrics, the argument you had with your boss today at work, or what to buy you child for their next birthday. Awareness is being in the moment and noticing the events and circumstances surrounding you at any given time.
A key component to making awareness work for you is narrowing your focus to a particular object or area. When it comes to a violent attack, the number one thing to keep a lookout for is the persons hands. What are they doing with their hands? Notice if they refuse to show them. Are they hiding something? Are they protecting a weapon? Theses questions need to be answered, especially if you are in an unknown environment where you are vulnerable to attack. The hands do the killing most of the time. That is why cops want to see the hands so badly on television and in real life. They have been taught to diagnose the use of the hands. You too can use this to give you a reactionary edge. Train Hard!