The two basic elements of using your pistol in a self-defense encounter are technique and tactics. These make up the foundation of a solid defensive shooter. If you do not have solid technique, you will never have the ability to deploy sound tactics. Technique includes basic physical movements such as drawing, front sight focus, and magazine changes. Tactics are actions one needs to take in an encounter such as moving to cover, improving your position, and creating distance.
In a recent class I taught, some of the students were having difficulty changing their magazines. Two of them wanted to "skip" that part so the class could keep moving. Not a good idea. Whether you are topping off your gun or doing a fighting reload, the magazine change should be completed without thought. Automatic.
First, if you are a righty, carry your mags on your left side. Carry them vertically in a pouch with the bullets facing forward. When you grab a fresh mag, run your index finger along the front edge of the mag and have the baseplate rest in the palm of your hand. Now you know which way is forward.
Reloading your pistol is predictable and should be practiced to the point it is completely reflexive - muscle memory. If reloading your sidearm is not second nature, it will take too much of your concentration and focus during a deadly encounter. When lead is flying you will need to focus on your adversary and your next move. Not on your magazine that "won't go in."
Your tactics are much more dynamic and fluid.The correct tactic in one scenario could prove to be deadly in another. For instance, if you are a legally armed citizen faced with a potentially deadly threat, a sensible tactic may be to draw your pistol and order the bad guy to the ground.
The bad guy's subsequent reactions then dictate your tactics. If he complies, your continued verbal direction from a  superior position would be the course of action. However, if he draws a gun, shooting him would be appropriate and necessary. If after the threat draws on you, your continued verbal commands would prove deadly. 
So meanwhile, as this is all taking place, you need to see and process details such as: what type of weapon does he have? Does he have body armor on? Are there innocents around? Did your shots completely stop him? Is there cover close by?
If you are distracted by techniques such as topping off your pistol or a fighting reload, you may miss the details that could potentially end your life! Keep both eyes open, break your tunnel vision, and SEE what is going on so you may plan accordingly!

.We recently had a student relate a story to us as an idea for a post:

"I bought some new carry ammo last week so I went to the range yesterday to shoot the Winchester rangers that have been in my Glock19 for the past 2.5 years and had one round in 31 that I was certain was a squib (which could obviously be deadly in a SD scenario). Turns out that it wasn't but the recoil was so light (like 22lr light) that I was shocked that I didnt see one stuck in the barrel when I broke it down. 

I carry the G19 in the appendix position and sweat all over it in the summer (hiking, biking, soccer with the kids etc, etc). Not sure if the issue with the round was caused by heat, moisture, or something else but it was definitely eye opening for me since you're pretty much fucked in a gunfight if you get a squib load. Especially since it would probably result in a tap, rack, kaboom. I'll be shooting/refreshing my carry ammo at least once a year going forward."

Once a year sounds like a good plan. It certainly can go longer (or shorter) depending on some factors, but why chance it?
Where do you carry your gun? Does it get particularly sweaty there? Holster selection and type can make this better or worse. Maybe you don't sweat a lot. If you wear a tee shirt between your body and your gun it can certainly influence moisture on your carry piece as well. Are you one of those people that like to powder themselves? If so, that nastiness can get in your gun and your magazines. Clean it out from time to time!

Do you have training magazines for the range? In other words, do you swap out your hollow points when you go to the range to shoot FMJ? If you do, you may inadvertently compress some of your cartridges or knick them, or drop them in the dirt. This will adversely affect your self defense rounds cycling. We STRONGLY suggest having separate training mags and self defense mags. Test your factory mags for function and load them up with your defensive round and stop playing with them. Rotate your "extra" round that is kept in the chamber from time time with the top three or four cartridge in your magazines. Use your aftermarket or older mags for training. Keep them clean but mark them with a sharpie and a numbering system, and keep them separate from your self defense magazines.

We advocate shooting hollow points through your gun from time to time to ensure proper cycling, mag function and to get a feel for a more powerful load. Potentially this is your life and lives of those you love at stake. Would you really cheap out and risk all that is precious with nasty, sweaty-ass ammo that may malfunction? Yes we know hollow point ammo is expensive. However, is a properly functioning sidearm worth $31 per year?

Once a year, shoot your carry ammo off at the range using good technique and "own" EVERY shot. No misses! Operational efficiency. Put yourself, or have a friend put you under stress. If a round goes "ppphhhttt", watch out, be careful and treat it like a squib... or if it goes click instead of bang, clear it, fix it, and get back in the fight! It's good training and good sense!

Thanks M.M. for sharing this with everyone!