See if you can find a place that rents handguns, that would be your best option. Let her handle and shoot some different calibers and models. I have seen plenty of women that can handle 9mm, 38 and 357's just fine. However for ease of use and low cost you just can't go wrong with a .22. Heck you could even get her a .22 rifle. Most indoor ranges will allow them, and it might be more accurate for her.
I would personally suggest a ruger semi auto pistol or a browning buckmark. I have owned both and they are great guns. I prefere the buckmark to be honest, but that's just me. I am little and like the feel of the walther .22, but I have heard mixed reviews about it. Haven't shot one either.
I was going to get my girlfriend a gun, but after looking around and playing I may get her an Airsoft rifle instead. They look and feel very real but are much safer and you can shoot them in your house if you wan't. We were going to get her a walther pistol or a 10/22 rifle, but then we shot some high end electric Airsoft rifles and she really liked them. She likes the MP5 with the silencer. And as an added bonous they can shoot full auto

. If you don't know what they are they shoot those yellow plastic bb's at around 3-4 hundered FPS. The one she looked at was 300 bucks though without a battery pack and charger.
She decided she wanted a new bow instead though so she got a new Hoyt Rintec in target colors. I sort of wish we would have gotten the air soft rifle now that we moved into a trailer park. We could play with it in the house if we wanted.
Paul