When my wife decided she was ready to start carrying, we went and looked over all the options. She had limited shooting experience so we decided to with a revolver. I'm glad we did. It has less moving parts. I figured that if she had trouble remembering the basics of the semi autos function in the store, I definitely didn't want her to be fumbling around with it in a high pressure situation where it could mean life or death!
We went with a s&w 642. It is small, light, and it has an enclosed hammer so it is virtually snag proof. She practices with it out to 7 yards, and she does pretty well with it at that distance.
To summarize, I think sticking with an easy to use gun, that she is comfortable with and practice as much as you can! Good luck!