One of my friends (and a member of this board) found "be alert" to be not very useful -- it says to achieve a condition, but doesn't give you any method for how to do so. So developed a kind of mnemonic to give one a specific way to "be alert." It is not the end-all be-all of situational awareness, but it gives a very good way to start. It focuses you on the people around you, which is where the (criminal) threat will come from. It also makes you a better witness.
Repeat after me: "Hands-Eyes-Hats-Tats-Shirt-Shoes"
Meaning:
Hands - look at them, this is where people carry weapons, if you can't see them, is that a problem?
Eyes - where is attention directed? why/? Are you being sized up? Is the person surreptituously watching you? Suspiciously looking around (as if for witnesses or cops)? You can't see eyes because he's wearing a mask? (This is a red flag
) Ignoring you? This also gets you looking at the face -- color eyes, facial hair, etc.Hats - is the person wearing a hat? What kind? if not, what color hair? Bald? Bandana?
Tats - Does the person have tattoos? This is not really about tattoos, it is looking at the skin but saying "Skin" does not flow as well in the mnemonic. What color? Are there in fact tattoos? Can't see skin because of coat, gloves? and it is warm out? hmmmm
Shirt - Color, type, short sleeve, long? Says "POLICE" across the back? "INMATE?" Too big, might be hiding something (might be a CHL!). Again, wearing a coat when it's not really appropriate?
Shoes - What kind? can't see them because he's behind something? Is he just behind something or hiding? Is he sitting in a car? What kind of car? And of course when your eyes switch to the shoes, take a look at the pants as well.
And does it all hang together? Wearing a Spurs jacket is not too unusual, but if it is over an orange jumpsuit...hmmm. Jacket might not be too out of place, but a duster, particularly if the hands are hidden, does he have a longarm under there? One time my wife picked up on some guy because his clothes, all of them, were brand spanking new and didn't fit all that well. Didn't take long to figure out he had just been released from prison. He wasn't threatening, he was just looking for a handout at a restaurant, but frankly it gets more of my attention than some kid wearing a boy scout uniform....
My friend's favorite exercise for this is to tell you to specifically go thru Hands-Eyes-Hats-Tats-Shirt-Shoes with one hundred people in the next week. Count them, and say (to yourself, unless you don't mind strange looks) "hands-eyes-hats-tats-shirt-shoes". This is to ingrain it as a habit. Look at everyone, people walking, people across the street, people in cars (learn to look thru tinted windows, wherever you see a person.
As for parking lots specifically, I would add to learn to look thru all the way thru car and truck windows, and not get tied up in the task of putting things in your car. You have to load the groceries, or the kids, but look around before and after each bag (or kid). If you are doing hands-eyes-hats-tats-shirt-shoes to everyone as you walk out to the car, you should be looking around pretty well.