YMMV...
Let's start here:
http://www.armedfemalesofamerica.com/archive.php?aid=668
I'm an enthusiastic advocate of seeing girls get into martial arts as an integral part of developing the mental and physical reality inherent in defensive firearms training. Along with the comprehensive physical conditioning and flexibility comes actual sparring with strict supervision - and that helps a girl understand what it means to get punched-kicked-slapped-grabbed (
very important to learn if the girl has never known such).
In selecting a personal firearm, I'd go for ergonomics first and foremost. (see about CZ's, and the Baby Eagle in .40, and absolutely the P232, and follow her interests from there) Next -
she absolutely has to like the specific gun - even if her focus doesn't align with specifics you might prioritize. (if at all possible, get her gun individualized with a little engraving - such things can be important...)
Get her her own (individualized if possible) gun leather - and don't flinch if she asks about available colors.
If martial arts training is out for whatever reason, work with her on strengthening exercises focused on her grip, wrists, elbows, shoulders, and abs - then target her legs all-out. Yoga classes, or Tai-chi are wonderful for breathing and focus. Remember, we don't get drowned in testosterone when crisis arises.
Read these essays together and discuss them:
http://www.gunowners.org/womensvoice.htm
And, when it starts getting down to caliber:
http://www.firearmstactical.com/wound.htm
And, for a concept of shoulder holsters that will really,
really conceal her gun under a nice suit or light jacket when she doesn't want to carry off-the-body and a waist-carry is unfeasable,
http://www.klnullholsters.com/
I have never seen enough repetition in any of my students or girlfriends' choices of favorites to say revolver or semi-auto; and I carry both. The American Derringer Model 1 is popular, though with just about everybody as an option that usually goes everywhere...
If either of you feel I may be able to provide any assistance, of course please write me, and I'll do whatever I can.
Last - get a copy of Paxton Quigley's book, "Armed and Female." I've loaned out 9 copies over the years - and they always end up getting passed from friend-to-friend, never (happily) to be seen again.
All the best!
Trisha