Having been to several defensive shooting schools and having owned 17 diffrent types of hand guns from custom 1911s to smithJ frames, I would suggest a springfield XD in 9mm as a starter auto. They have a good price andare very reliable. Now a good revolver is hard to beat for ease of use, espically for women, but a DA trigger is a little harder to become good with. .40 is a good round but it's only slightly more effective than a 9mm. I have seen the FBI data and data from DrFacklor..45ACP is the best preformingbut at the cost of grip size. If you must have a .45ACP the Springfield XD would again be the best choice. I am a Glock fan but the Glocks are more expensive and the 45 is way to big for most espically for a woman.
The best advise I can give you is getyour pistol and then find a good school to go to. A $100 dollar Hi Point will be more effictive in the hands of a trained shooter than a $2500. custom 1911 is in the hands of a" lets go to the Range every couple of months" novice.Good Luck feel free to PM or E mail me , Jim