Get in and see which one bites, but have a target in mind already...
Also be aware that some girls are just flirty flirts and don't get too baited by those, but it happens, sometimes you really can't tell if she's just the flirty one in the group, or maybe is just teasing or tintilating you just to kill some time or something, or if she really is interested.
If you get rejected, you don't want it to be in front of the other girls, ideally you will be social and nice to all of them, but focus on your target and isolate her. If things go sour if her, chances are she'll tell her friends, but maybe some other girl in the group will be interested and will give you a chance, if you didn't fuck up that bad, but in this case, I would wait for the girl to at least give me some AI and make it easier for me to talk to her. But yeah, most of the time you only have one shot, so pick the best one and go for it (but again, I wouldn't go too hard for just one if like I like two or more equally. I remember opening two girls, and I was going for the blonde one, but it turned out her boyfriend was coming. Brunette was also a hottie and honestly was funnier and more open to me, so I just kept talking to both, and got both their IGs when they left. Later on, I went on a date with brunette, she asked me "you wanted my friend, didn't you?", and I was like "well, to be honest, you're both really attractive, I wanted you both". We made out a lot and it went well in general in the date, but I didn't pull her because I was going out later to
meet some other girl, in the end we ended up not having sex, but I would say that having the balls to approach both and keep a convo equally with both of those hotties really made her even more attracted, in this case. It really depends on the situation).