Get thee to a good range, with a gun rental desk. Learn from somebody that’s a good teacher. Try lots of guns. Read everything that Massad Ayoob wrote.
The right answer is going to be the largest caliber gun that you can fire accurately and comfortably. I know some women that are perfectly comfortable firing a .357 magnum or a .45. Some others that prefer something smaller like a .380.
The truth is that *any* pistol is better than no pistol. If you want to carry... smaller and ligher is better, mainly because the easier it is to carry the more likely you are to actually have it with you when you really need it.
I carry a .45... and one of three that I have. When I can carry a full-size pistol in a shoulder rig I carry a Sig-Sauer P220 Elite. When I have to carry in a pocket I carry my Kimber RCP. It’s very small and light.
What he (Ramius) said.
I would advise a revolver versus an automatic for a beginner, but Ramius is correct on all points.
If I were behind the counter, I’d start you out with a Smith & Wesson .357 Model 19 or 66 with 2 1/2 inch barrel. It can shoot .380 if you can’t handle the recoil of a .357, and you can always work up to .357 with practice.
Besides being incredibly reliable and accurate (adjustable sights), it just looks nasty.
Do NOT buy a pink gun. If you have to draw it, you want to be taken seriously, not worried about accessorizing with your make up. Nor do you want anyone to think it is a toy.