There are some very good and respectable gun forums sites where you can learn from other common folk like us about revolver vs semiauto, possible hearing loss from magnum loads etc... I highly recommend knowing what you are going to buy before you go to a gun shop to make the purchase. Most gun shop employees don't know much about guns and they are almost always heavily biased to sell you what is good for them, not for you. Take a gun safety course, shoot as many guns as you can by renting or bugging someone to take you along to the range.
And if you ever have to shoot someone, say that you were trying to STOP them, not KILL them. Semantics can make the difference between you simply defending yourself and you being charged with manslaughter. Good luck!