I kinda use a modified isosceles stance, knees ever so slightly bent, gun at
center, thumbs over grip (on a 1911. )
FWIW stance is important, but sight alignment and trigger squeeze, however, are paramount. Having a good natural point of aim helps too, especially when coming up to hit the first pin. Stance is great but if you don't pull the trigger correctly and don't know where your gun hits at 25 feet then those pins are not going off the table.
-Stop rushing. Yes, it's a race, but when you're starting out you are a bigger enemy than your opponent is. When you're starting out accuracy is way
more important than speed. Those who are accurate will typically beat 50% of shooters right out of the gate, because everyone else is too busy spraying
bullets at the pins (or at the table). Bear in mind that a miss consumes way more time than just slowing down a tad. It also keeps you from
running dry before you get to the last pin. Later on in the day when the pins are heavy and every other guy has an extra 1 or 2 on the table, may
not matter so much, but when the pins are fresh, having to reload sucks.
-Flinching- if you are new, you'll probably do it to some degree or another- and it gets worse when you are rushing, because if you try to shoot faster than you're really capable of, then you tend to mash the snot out of the trigger too hard, pulling the muzzle off target. If you are flinching badly use ball + dummy, and other techniques until you work it out of your system.
-Stop looking at the other guy's table!!!!!! Never, ever look at the other guy's table until either yours is clean or the match is over. Doing this wastes valuable seconds of time. Many people have lost matches because they wasted the 2-3 seconds it takes to look at the other guys table. Even when reloading this still wastes time and will slow down your reload.
-Use an appropriate caliber. You should only be shooting at pins with heavy bullet .357 mag, or .40 S+W on up. Anything below this point is almost a waste of ammunition and match fees, as past the first relay things like 9mm and .38 SPL RNL are beyond worthless. Once the table has a few craters in it, those calibers will not roll the pins over the defects. (This is especially true at a place like NL where the tables are just about below the shooters, making table hits more likely all around. ) The pins get heavy too after a few relays go by. Then the pins get bumps in them. Ideal calibers are .44 magnum, .45 Colt, .45 ACP, and 10mm (with hot 180 or 200 grain loads) If you know someone that has a spare gun in these calibers you are better off just buying some ammo and borrowing their gun. There is a reason .45 ACP is pretty much the dominant pin caliber in area shoots. Now, someone is going to go "But .45 acp is expeeeeensive!" It's not as expensive as it is to waste twice as much 9mm to do the same job. (A 9mm will rarely, if ever clean a table with 1 magazine, which is a detriment by itself. ) Running a 9mm against pins is it's own brand of self-torture / masochism- and it's even worse for newbs because they could be getting fairly solid hits but the pins refuse to leave the table.
-Clean your gun, magazines (and case gauge your ammo, if you use reloads) before a match. I can't stress this enough. I have lost many matches because I didn't do either of these because I was too lazy or some other excuse. I have also seen a bunch of other guys lose a match because of a gun jam. Gun malfunctions will totally destroy your concentration because the whole time all you'll be thinking about is "when is my gun going to fail next" and not "how do I clear off this table of pins". Shooting pins with a constantly malfing gun is just an exercise in futility. This is true whether the gun is a semi pistol or a revolver. (I've seen both fail on the line, revolvers are not immune. )
-Dry fire practice- Practice bringing your sights up at a dot on the wall and pulling the trigger without moving your front sight. Reset trigger, repeat,
etc.
-Live fire practice- Get yourself a pack of 3" shoot n see targets. If you have enough space, put up 4 of them about a foot apart on a target stand off the ground at pin height if possible. Practice coming up off the bench and cracking a shot off at the targets. If you can consistently hit a 3" shoot n see at 25 feet you are taking pins off the table, or at worst, at least hitting them every time. Even if you can only put up ONE shoot n see, practice coming up off the table and hitting it.
-Mike