As a girl playing GTA 5 and GTA Online, I really don't do anything different than most guys. I'll troll people and sit on top of buildings waiting for people to drive by so I can snipe them or go close by to the helicopter pads and wait for someone to get inside one and then rocket launch their a$$. Although, the only thing I do differently I'd say is do jobs by myself. Like the ones from Gerald or Ron or Simeon. It's just better to play by myself and easier. I've tried to go into Heists or Jobs with guys in the lobby, but they tend to exit out of the job when they see I've joined, just because I'm a girl. I'm just like what the heck, I'm level 76 in GTA Online, what more do you want from me?? I also don't go on chat a lot. Mostly because I'm tired of hearing little 5 year old boy voices yelling in my ear, but also because if I say anything to anyone, a few things could happen: 1. Someone says "omg there's a girl in here" (Inevitable) 2. Someone will make it their mission to seek me out and kill me. or 3. I'll suddenly get messages and friend requests.
Friend requests are pretty much the norm though. Even without talking to anyone they know my username is pretty girly so one session of playing GTA Online usually gets me at least 2 or 3 friends requests from random people. I don't accept them unless we end up playing together and creating havoc around Los Santos.
But to answer your question OP, I personally don't play it like you probably expect a girl to. Like some of the guys on here will say theirs wives play it and just drive around and go shopping. No, I actually play the game, missions, heists, buying fast cars, all that good stuff