What is the most likely threat to occur? And the worst threat? How likely is the worst case scenario to occur?
Are you prepared for the most likely threat? Do you have a plan? Have you Red Teamed the plan?
Do you have a PACE ready?
Visualize the various parts of the plan, what you need and how you will use what you have. Communicate that plan to all those involved and drill it. Stress test it. Red team it. Give anyone involved in the planning and selection of actions, a chance to poke holes into it.
Sometimes you have time to fully assess the situation. Other times, you assess threats are they are presented and select the best way to act based on the information at hand.
Act, don’t react. Always try to be several steps ahead.