Congratulations on your first handgun. A .22LR revolver is a great addition to any collection.
As for the legal issues (especially regarding having to shoot someone), Mister Miyagi from the movie Karate Kid summed it up nicely, "Best block, no be there!"
I imagine restraining orders, calling 911 at appropriate times, evading & avoiding risky situations, training yourself for likely scenarios and advisory discussions with your lawyer would be helpful for your specific situation.
There are some helpful books about self-defense I can recommend.
"In the Gravest Extreme" by Massad Ayoob
"Armed & Female" by Paxton Quigley
"Self Defense Requires No Apology" by Jan Jones
"Self-Defense: Steps to Survival" by Katy Mattingly
A good DVD video is "Armed Response - Tactics and Techniques for Defensive Shooting" by David Kenik and Ralph Mroz. It's part of a series of training DVD's they produced. They also have book version covering the instruction contained in three videos.
Other people have covered the Weaver, Modified Weaver and Isosceles stances. Also mentioned were helpful hints about trigger control, squeezing and follow through. I can echo the 'start slow and smooth, let speed come to you later' advice.
Taking personal defense and home defense courses would provide invaluable knowledge and training. Also, the instructors could observe your techniques and offer specific corrective instruction, if necessary.
In home defense discussions, "Layered Defense" is a concept mentioned often. The home becomes an onion-like zone with layers of protection. Some things are fairly obvious, like keeping windows & doors closed and locked. Other things, such as having thorny bushes & shrubs carefully placed around the home in order to discourage people from using windows as a means of entry may be considered more subtle ways of creating boundaries and obstacles against unwanted intruders on your property. Dogs often make good alarm systems.
http://www.nononsenseselfdefense.com/homesecurity.html
At your home and personal shooting range, pehaps a fence may help control who can access your site and from which directions they'll be likely to approach from. Dry twigs, trip-wires that shake empty tin cans, and other simple early-warning systems may help you detect approaching people or vehicles while you're wearing ear-muffs on a firing line.
While lethal force is an option, it is also the last resort. Consider adding non-lethal options to your array of skills and equipment.
A pistol is often more difficult to aim than a rifle. It is not that pistols are inaccurate. They're difficult to shoot well because of their shorter sight-radius, their limited surface area and leverage available to hold them & keep them steady, and their smaller mass offers less resistance to recoil.
But with practice of good techniques, a shooter can learn to engage targets with efficient proficiency.
The "center of mass" is where you want your shots to impact.
There are two major schools of thought regarding sight pictures.
http://www.targetshooting.ca/docs/pistol_sighting.pdf
-- The older and more traditional method is the "six o'clock hold". The shooter aligns their sights and rests them at the bottom of a bullseye on a paper target and the shots impact the center of the bullseye. Because of the variables involving the size of a bullseye and the distances from a shooter to a target, the "six o'clock hold" is usually reserved for target shooting competition techniques.
-- The better method of sighting-in a handgun is the "center of mass" hold. When a shooter aligns their sights properly and aims at the dead center of a target, the shots impact the center of the target. The point of impact corresponds with the center of the top of a front sight. Not higher, not lower and neither left nor right from center.
There is also point shooting. I've provided links below, in order to do it justice.
Again, congratulations, good luck and enjoy your revolver Annie. :-)