When it comes to the whole buying drinks issue, I'm of a few minds about it. Obviously, it's one of the most tactless & most AFC of openers, thusly why it's such a Disqualifying act.
Then again, I'm a bartender, and it's also a ritualized thing for me... ( "Hi, welcome... oh? Is this your first visit here?! Welll then.. this round is on me! I'm pleased to be your host! HOw's your world tonight? Looks like you... blah blah blah" ... DIG?)

On top of that fact... I drink... ALOT!!!!!

I've never really chased anyone away by buying drinks for them, or all their friends, guys and girls alike, IS a qualifying act in some ways...
( Normal people, & by 'normal' I mean non PA's , often treat people they LIKE or are friends with in ways that are considered giving and gracious. IN other words... dont be fucking cheap! Show people you are invested in them ALL, and keep them ALL under your carefully woven spell), or just she & I... especially just she & I!

I do though, tend to run with folks who ALSO bartend, and have a particular mode of operation when their out, and demand that all whom would be in their vicinity adhere to this manner of behaving as well. You tip heavy, are always gracious, and always respectful. Any challengers or feckless dolts who are incapable of this conduct are swiftly dealt with, educated, and summarily brought up to speed with our unique conduct amongst each other, or devastated by an epic verbal assault & sent off to suck with the rest of the 'bridge and tunnel' trolls. ( Game or not, I have no tolerance for people absent of 'Bar manners' )

It's really up to you if you wanna buy all the drinks all night or not. But follow your own instincts as to her buying temp. If you feel like your digging into your pockets too soon, you probably are. Just dont offer to buy her a drink...

Here's one that some of you may not have considered...
If she dosen't know you to trust you & may have left her drink with you for a moment ( particularly if its getting warm & the ice is melting ) Just go on ahead and get a round fro both of you, citing that :
" I turned my back for a sec. & there was this spooky guy oogeling you as you walked away... Your drink was gettin old, & I didnt want to take any chances that The freak had put something in it.... Here... CHeers!"

DrInK uP... hiccup... yOu PusSiEs... hicc...
BLLLUUUAAARRRRRRKKGH.... buuwaap

God... Just never buy her a drink the first time you meet her, its just gonna boost her ego to have the control again (Expecting that shes a HB), and your value will take a deep dive.

If you want to do something nicer than buying her a drink, hear this. Chivalry, for example open doors for her. Things like that can be done.

if it get's to a point where the convo may die if i don't give in i'll go to the bar with them, get them to buy me a "suprise" drink, and i do the same. keeps it playful. the drinks are even convo topics if you get something interesting, i.e. pornstar, paralyzer, tijuanna taxi, etc, etc.

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"Jesus would martyr his mother to ride to hell between those thighs" - Puscifer