If you're a gun novice, I recommend a double action magnum revolver of at least .357 caliber for the following reasons:
1) DA revolvers are simpler, and therefore safer. There's no hidden chamber for rounds to go disappearing into, which is probably the number one cause of accidental shootings.
2) DA revolvers are simpler, and therefore easier to use. There's no safety or hammer to be fumbling around with. They're the ultimate user-friendly firearm. When you're awakened by something going "bump" in the night, you won't have to do anything except pick it up, point it and pull the trigger.
3) Revolvers work, period. They don't jam and are not sensitive to varying ammo pressures. Automatic pistols can be finicky about what rounds they'll eat. With an automatic pistol, most experts recommend that you cycle about a hundred rounds of your chosen carry ammo through it before carrying it loaded with that ammo to make sure that it's reliable with that particular load. In case you didn't know it, premium quality personal defense ammo is expensive (about a dollar a round, at least), so plan on spending at least $100 more than whatever the price of your automatic pistol is to get up and running. With revolvers, you don't have to deal with any of this crap; you're good to go right out of the box. This is a major advantage, especially if you're on a limited budget.
4) A magnum revolver will allow you to shoot cartridges of many different power levels. It's like getting several guns for the price of one.
5) 125-Grain JHP in .357 Magnum is widely considered to be the gold standard of handgun stopping power, with a one-shot stop rate of 96%. This is a revolver round.
As azcdlfred noted, The
Arizona Gun Owner's Guide is an excellent resource. If, for some reason you can't get a copy, then check out this excellent video by Marc Victor, the Attorney for Freedom. It's an excellent, no-bull$hit crash course on what
not to do with your shiny new gun if you want to stay out of jail:
http://www.attorneyforfreedom.com/i...ney-marc-victor-self-defense-deadly-force.htm
Here are some other good videos featuring Mas Ayboob:
Judicious Use of Force - Part 1
http://www.youtube.com/watch?v=qW_xaTf5oqI&feature=related
Part 2:
http://www.youtube.com/watch?v=oGJIyxm2s_M&feature=related
Part 3:
http://www.youtube.com/watch?v=gNCRL9SN2QA&feature=related
Part 4:
http://www.youtube.com/watch?v=AJazmbDH7S8&feature=related
You can find lots of good stuff on the 'net. Hope this helps.