No amount of tactical training will do you any good if you haven’t got the ability to recognize when to use it. The industry catchphrase for this is “Situational Awareness”. Simply put, pay attention to what’s going on around you. People are generally less aware than they realize. This is why accidents happen.
There are techniques for paying more attention than your average citizen does. The most bang for your buck will come with the realization that there is no such thing as multitasking. It is scientifically proven that the human brain cannot actively participate in more than one conscious activity at a time. All you have to remember is which actions can be regulated by the subconscious brain. For the record, besides autonomous body function (breathing, digestion, etc) everything takes conscious practice to get. That’s why babies and children fumble with motor skills. Picking something up is unconscious to you now, but you’ve been doing it a while.
It’s like Speed and Security. You can’t have both. The more you have of one, the less you have of the other. They are a sliding scale. That’s something to consider when going about your day as well. If you are rushing around in a panic state of accomplishment, the little things suffer. They are easy to miss. For every extra thing you are “trying to do at once”, you are doing them all that much worse.
While it can be detrimental to an operation to “What if…” incessantly, when properly applied, it can be a useful mental training exercise. At the very least, if you have considered an option, it’s less likely to surprise you in the event it actually happens (does not apply to zombies or an apocalypse. That never flies around here). In fact, being in a constant state of “What if” is the same as being Situationally Aware.
For example: If you are in a restaurant, what do you pay attention to? The other patrons? The staff? Most attacks in places like this walk in or happen from the outside. Same with public transportation, except airplanes (on a bus or train sit toward the aisle; planes toward the window). Every single situation is unique for any various reason, so there’s nothing you can decide ahead of time to combat a specific scenario. If you spend all your time training for an active shooter scenario, you’re going to find a madman running people down with his car.
So, besides training the physical fundamentals, what can you do? Pay attention. People watching is your new hobby and you love to do it. There is a trade-off of course. It’s hard to engage in conversation with others when you are actively paying attention to the scenery. It’s a constant juggle.
Aside from that, you can try to have a plan. Are there avenues of escape?
Is there cover? Do you have a weapon? Do you need one? Can you get one? How far can you actually make it given your level of fitness? I can’t give you a specific checklist. Only the question “What if” and training in the fundamental skills needed to deal with them.