Approach her, beckon her to approach you, or have the cocktail waitress/bartender do it for you by buying the lady another drink... and maybe follow it up by sitting next to her if she accepts it.
It's a dance. And most women prefer men to lead.
It's not brain surgery. The fact is that most single women in a bar (not necessarily the ones in "girl groups") are there to get laid... especially when they're making fuckme-eyes around the place... she obviously saw something she liked in you, but you showed her you weren't ready to take it to the next step.
In that situation, it's, generally, the man's place to make the first direct contact.
If you turn out to not be the kind of man that will get them there that night, they'll usually just find another as opposed to holding your hand and walking you to their bed. Guys like you are one of the reasons I got so much play in the years that I bartended... I was safe to start talking to, always stuck there until the end of the night, and if it's what they really wanted, they usually got a lot more open about their desires the closer it got to closing time.
