If it is a serious topic you’re best not to talk to her. If it is light-hearted, then you’re probably safe to proceed.
It is okay to jump in as long as you do it in a nice manner. Ask her questions relating to the subject. Say, “I’m lost here, what are we talking about. Gimme the spoiler?” Don’t just walk up to a group of people you don’t know and start standing there and listening. That’ll be a big creepy turn-off.
Introduce yourself if necessary. If the group is talking about a recent movie, join the conversation and share your impressions. Talk to the entire group of girls. Don’t try to single out the girl you’re trying to talk to immediately. Depending on the girl, she could be worried about offending her friends, or feel bad that they aren’t being given the same amount of attention. [3] X Research source
Start making little side comments that other people won’t be able to hear. Keeping her interested in what you are saying will make her distracted from the rest of the group, and eventually, focusing more on you.
If you they don’t leave, make sure to include the other members of her group in the conversation so they won’t be left out. However, make sure you are still fun of the conversation so that you are also getting a chance to talk to the girl while having fun. Most girls think it’s nice when guys are nice to their friends.
If you never meet back up, wait unit the end of the night. When her group is leaving, pull her aside quickly and tell her what a great time you’ve had. Tell her you’d love to meet her for coffee or a drink sometime.
How do you all know each other? How often do you all hang out? What are you all drinking? Who has the best one?
The follow up is the most important part of a conversation. Nobody knows how to talk to a stranger without listening to what they say and responding. [6] X Research source
At the same time, don’t only talk about yourself. Self-absorbmant is a pretty big turn-off.
Lots of “pick-up artist” schemes recommend subtle insults as a way of getting a girl to be attracted. While this has mixed results, it’s always a terrible idea to try in a group full of girls. Little jokes can work fine. But there’s a difference between saying something teasing and flirty like, “I can’t believe you hated Iron Man. Have you no soul? Prove to me you have a soul” and telling a girl that her perspective on birth control is “childish. "
Don’t try to show off as part of a group. Jokes and gimmicks are more likely to get you a drink in the face than an invitation to coffee.