1) Avoid the mall.

2)When entering a public venue, be aware of the exits, both marked and unmarked. Have a plan to get to an alternate exit if for some reason your preferred exit becomes untenable.

3)Be aware of the people around you, and what they're doing

4) Assess the situation, and take appropriate action (rapid exit, delayed exit, shelter in place, seek cover/concealment and respond to the threat, etc.)

The key for me is to have a plan in advance, that way you're not thinking about WHAT to do, you're only faced with HOW to accomplish it.