(If she's not familiar/it's her first.) There are so many, I'll just say: Take her to a couple of local gun stores. Have her handle a few at each. She'll probably pick due to what her eye likes. Go from there. Pistols? Smaller caliber, less kick, just do a grip check. Single stacked mags. Shotgun? Smaller loads, .410, 20 gauge, shorter barrel. Actions a plenty, what's she pick up first. Familiarize her with that and see if it shoulders comfortably. Rifle? T-Rex. (JK!) Again, weight of the gun, smaller caliber, (I ain't typing all that out 5.56- 30 cal range, smaller powder loads.) Barrel length, is she comfortable handling it? Everyone is different, find her comfort zone, especially if you're considering a gift. Use the "hey, let's go look at guns" and the old "yeah, but, if you had to pick one and you could..." Good luck!