1. You have to be focused enough to avoid potentially bad places, events, etc.
2. You have to have a gun with you.
3. You have to be aware enough of your surroundings to notice that something isn’t right.
4. You have to assess what’s not right to determine if it’s a threat.
5. You have to – in real time – decide if it’s a deadly force threat.
6. You have to act on the threat. Most people freeze or don’t believe what’s actually happening. You have to employ appropriate tactics such as moving, sheltering a loved one, etc. Of course you have to be aware of your environment to make the best choice here (see 1. above).
7. You have to give appropriate instructions to anyone with you.
8. You have to access your weapon in time.
9. You have to employ effective challenging techniques, if appropriate.
10. You have to track the BG’s movements in real time – we’re talking fractions of a second here – to understand what he’s really doing at that exact fraction of a second.
11. You have to track what’s behind the BG so you don’t potentially hit an innocent.
12. You have to be aware of anyone else in the area with a gun who might mistake you for a BG with a gun.
13. If you have to shoot, you have to hit the BG, preferably COM.
14. You have to track the just-shot BG to make sure his weapon is out of reach and prevent same weapon from falling into the hands of his buddies or a bystander.
15. You have to communicate effectively with the now-shocked/hysterical bystanders to keep them safe, let them know what just happened, and make it clear that you – the guy that just shot someone – is in fact a good guy.
16. You have to get yourself and loved ones to safety.
17. You have to get your gun out of sight.
18. You have to call 911 while making it clear that you are the good guy. Included in that call, among other things, has to be a description of you so that responding cops know who you are. You want to do this yourself for what I hope are obvious reasons. Also of course, you have to know everything else to say and what to include in this critical call.
19. You have to initiate first aid to any innocent injured.
20. You have to make sure you’re not shot by responding police.
21. You have to know how to interact with responding police: how to act, what to say, what not to say, etc.
22. You have to call your lawyer. Do you know who’ll you’ll call? Bail will come later.
23. You have to call your spouse, partner, parents, whomever, if they aren’t with you to let them know you’re OK and won’t be home for dinner. Or maybe for a few days. And to let them know that the press will soon be pounding on their door. And how to handle that, if you haven’t already discussed it.
24. You have to call some trusted, competent third party to go and be with your spouse, partner, whomever to help them through this stressful time and to deal with the jackals in the press.
25. You have to be able to articulate a clear self-defense case to your attorney. This assumes that you know what those elements are, and what things (witnesses, etc.) need to be tracked down pronto because they will disappear in short order.