“Hi, can I buy you a drink?”
Believe it or not, very few guys buy women drinks these days! So you’ll stand out as having an old world, gentlemanly vibe if you offer this. And of course she’s happy not to pay for her own drinks (be real now). Once she’s said yes, out of politeness, she’ll talk to you for at least ten minutes. That’s ten minutes you get to impress her that other guys don’t get.