I would never set myself up as an expert pistolero, nor take on airs that I'm somehow elevated to such lofty altitudes as the real competition shooters out there. That said, I have learned how to hold on to a pistol over the years, and it seems to work.
If it was just a matter of not letting go, a little twine and some duct tape would be all that's needed. But... that's not the case. When we look at a proper 'grip' (or hold) on a pistol, it's about much more than simply hanging on. It's about draw, control, precision, and repeatability.
The ultimate goal in most pistol shooting is to hit the target. Sometimes that target is a small bulls-eye on a paper target far away, and sometimes the target is roughly the size of a drug crazed maniac bent on mayhem and destruction. The target may vary, and the speed with which it must be engaged, but the goal does not change. Hit the target... slow, fast, near, far, in daylight or dark... the goal is to hit the target.
Pistols can be difficult to shoot well, and therein lays the magic for many shooters. The challenge of holding a little bucking chunk of steel in your hands while it explosively sends small projectiles downrange.... and actually having the bullets strike the target like we wish them too... that challenge is what brings dedicated shooters to the range week after week. Whether a competitive bulls-eye shooter, an IDPA pro, or simply someone who carries a pistol for defense, millions of pistol shooters work on this skill on a regular basis.
To those who have managed to gain a leg up on the matter, proper grip of the weapon is resoundingly key. Trigger pull, sight picture, proper draw, follow through... all these come into play. Proper grip, on the other hand, is the foundation of accurate pistol shooting. Without it all the others simply don't work well.
What follows is intended for shooting a semi auto pistol, although most will apply to revolvers as well. Left handed shooters can simply swap 'Right' for 'Left' in the descriptions.
First, the pistol should fit into the 'pocket' of the hand, with the recoil directed into the web between thumb and fingers. Ideally, the arm should extend to find the pistol directly in line with the major bones of the arm. This helps control recoil and speed recovery.
The thumb should extend forward, pointing at the target. The trigger finger, in safe position along the frame, should also align with the target as well. The position should feel natural, almost like making a 'pistol' out of your hand and pointing it at the target.
The hand holding the pistol forms the basis of the grip, and it's very important that it be firm and stable. All control and accuracy is built on this part of the grip, and it must be tight. Not just a little tight, but so firm the muscles in the hand and arm are just short of beginning to shake from the effort. Todd Jarret, world champion shooter and experienced instructor, has been heard telling people to 'Grip 20% Tighter' (no matter how hard they are already holding on). After hearing his advice, I tried it and can't find fault. It truly helps with accurate shooting.
Once the foundation of the grip is built, the off hand is brought into play. Wrapping around the base hand, the left hand thumb covers the right hand thumb, and also points at the target. The top thumb should be pressed firmly against the one below, and thus against the pistol. This aids in recoil control and recovery. Make sure not to have the thumbs touching the slide, as this may cause a miss-feed or jam.
The fingers of the left hand wrap around the fingers of the right, as if to pull it back at the shooter. Many shooters actually do pull the pistol back with the left hand while thrusting it out with the right (I am one of those). Some shooters simply support the base hand. In either case, the offhand should grip the base hand very tightly. Imagine how hard you would be holding the pistol were someone trying to yank it from your hands... and hold that tight all the time.
Done correctly, and practiced, this simple grip will vastly aid in both accurate shooting and rapid recovery from recoil. There is no reason for any normal pistol to break the grip with recoil. Even .44 magnums can be tamed by a proper grip, although anything larger may very well break the grip structure no matter how hard the shooter hangs on. Since .500 magnums are so seldom carried for self defense, or used in competition, this matters little.
Perhaps this short video clip will help illustrate the point.
A proper grip is only one factor in accurate pistol shooting, but it's arguably one of the most important. It should be practiced and worked on till it comes as second nature, both in dry fire and live range work. Once a good, solid, grip is built... the rest can be applied one at a time till the magic happens. Accurate pistol shooting, under almost any condition, with almost any weapon. First... build the foundation. Get a grip on it.