Just thinking about a technique that has paid off in the past.
Find a corner, well lit and trafficked .
Set your lens to about 1-2 meters, f4-8, depending on format and auto everything else.
Look as invisible as you can. Eye contact is to be avoided.
Fire away by instinct.
After about three changes of lights, you will see patterns appear. The flow becomes a wave of little stories.
Peoples faces go from a nameless mess, to the faces of these stories. You notice things on processing that become familiar over time. You feel that you know these people.
All of the above were taken using an EPM2 and 17mm at f4.