[WC145]

I was always taught (first by my Dad, a military weapons instructor, then by other military and LE instructors) that when shooting a handgun for defensive purposes you always start with a strong one handed grip - same grip for pistols and revolvers - similar to the Miculek pics shown in the link posted above, then you support that grip with your free hand. The reason being that in a fight you don't always have the luxury of shooting with two hands, an opponent may try to wrestle your gun from your hand, and, worse case scenario, your gun makes an excellent blunt instrument if it comes down to having to beat your opponent with it. That's the way I've been doing it for 40+ years and it all still makes excellent sense to me, I've taught many people to shoot the same way for the same reasons.

Honestly, I've never understood using the "high thumbs, palms squeezed together" two handed grip popularized by competitive shooters for defensive shooting. That method may work well in the controlled environment of a shooting range, but when your gun is supported equally between your two hands you can't remove one and still expect to have control of it. If you have to change or shift your gun hand's grip when going from one handed to two handed shooting or vice versa, you don't have a solid grip on your gun to begin with.