I personally think it's not as hard as it's made out to be. Social circle game is easier than "cold approach" pickup, but that isn't the point.
All you really need to do is walk up to a girl confidently, give her some eye contact and start a conversation. Say something like "Has anyone ever said you look like Katy Perry?" as just an arbitrary example. She may respond with yes or no, which is good, because she's investing. From there, ask if she can sing and tease her on it.
Start touching her early on, like a little brush on the arm or a handshake etc and slowly amp it up as you continue talking. Tell her to come with you to another location inside the venue, grab her had and lead her. This is more touch, more confidence showing and just shows you're a man. Just examples.
Make sexual innuendos, sexual jokes and just keep the conversation flirty, sexual and fun. Mistake her for saying sexual things, accuse her of hitting on you and just bust her balls. It's fun, shows you're not intimidated and shows that you're high value.
Just leave her better than you found her, have some fun and don't really make a big deal of things.
I remember back in my earlier years (primary and high school) that I was totally uninterested in dating, however that is probably the period where I had THE MOST amount of girls chasing me. They can left, right and centre, and I just blew them off because I was uninterested. If you show that you are at some place just to have fun and have a good time and are NOT there just simply to pick up, you'll feel less "threatening" and have a better chance of picking up. Though there is a time and place to be forward with your attraction to her.
Anyway, take it as you will. My two cents.
Good luck.
