Three things come to mind:
Maximize distance from the shooter.
Minimize the volume of space you can't see (such as what is behind you).
Keep your options open on means of egress.
You ability to achieve these ends will vary depending upon the layout of the place you are in.
If a shooting takes place in a crowded theater or restaurant, I shudder to imagine the chaos and the likelihood of my shooting an innocent person who darts into my line of fire in the confusion.
NRA Life Member - Orange Gunsite Member - NRA Certified Pistol Instructor
"When plunder becomes a way of life for a group of men living together in society,
they create for themselves in the course of time a legal system that authorizes it and a moral code that justifies it." Frederic Bastiat