BrianB sums it well enough. Whether shooting or knife throwing, one must learn the basics and practice a LOT.
My job for many years was to train new LEO recruits. After classroom training, the first was always the stance, 'Basic' [facing target squarely] or 'Weaver' [sideways with weak elbow resting on side for more stability].
Carbines were 'Weaver' stance only.
Here is a video that quickly demonstrates each:
http://www.ehow.com/video_2358156_prope ... oting.html
Advanced skills include 'front site', [speed] and 'instinct' [acquiring target without using sights]... start with laser, then progress.
Prone, with any firearm [stabilizing body by locking into ground]... most 'grunts' on here prob know that one. LOL
Caliber: For sidearm self defense, 'general rule' is .380 minimum to .45 max.
Many variables and compromises in that issue, especially concealment.
Still, a couple hits with a .25 beats a couple misses with a .45
Most practice can be done with a .22 sidearm. I do 95% of my practicing with .22s and the practiced skills transfer nicely to all my larger calibers.
At the range, I shoot my .22 for about 40 mins, then about 3 rounds each [usually] through my .380 through .45 if they give a decent group of 3 in the 9 ring at 30 feet.
Still have to send a few boxes of .38s or .45s down the range... every now & then.