That's the whole reason I got my concealed weapons permit, heck I can handle muggers and crazy people but it's those PA Mountain Lions that have me worried. LOL

Carry a gun you will shoot often, either a small light frame revolver or a light auto. a .357 revolver is a nice choice because for 1 it can't jam, and 2 you can shoot it fairly inexpensively with .38's on the range. But beware there is maybe nothing more ear splitting in a small package than full house .357's in a revolver. Made that mistake ONCE and only once. []

I carry a light 9mm auto (Firestorm Mini9) that is DA/SA holds 10 rnds and is infinitely cheap to shoot. I also have a .40 and while a decent round the 9mm is cheaper and I find myself shooting it much more. You can load +P style ammo (Corbon etc) and it's not something you'd want to have fired at you.

Whatever you choose become familiar with it UNDER STRESS. Chancesa re you'll never need it in a stressful situation but man you better know what you are doing with it if you find yourself in one.
The old addage is "It's only a good sidearm if you'll actually carry it" PIck something comfortable light weight, cheap to shoot and that you will practice with.

I chose the Firestorm Mini9 (Same as a Bersa Thunder 9) because it's inexpensive and something I don't feel like I have to baby or worry about scratching. I can treat it like a tool rather than a "Safe queen". It's been extremely reliable and I trust it. It's no match pistol but if I need it 1 out of those 10 rounds is gonna make a hole.