Also, 1 - Constant situational awareness.  Always be aware of your surroundings.  Observe people in public places.  See something, say something. 2 - Have a plan.  Be mentally prepared.  We all know generally what the main threats are.  When out and about, have a general plan.  Mentally prepare yourself to act, escape, defensively fight if you must.  Identify potential improvised weapons, cover, concealment, escape routes.