This was my first time using this approach and it worked twice that night. Being a server at one time i know how annyoing people can be so normally starting off with something more along the lines of a day approach works well (humorous, smart, innocent and witty). First take notice to where she prints reciepts and approach so you have clear access to the buttons.
ME: Hows's your night going? (big smile confident approach)
HB Bartender: omg so busy! some asshole just blah blah.
Me: i see. well at least you have 5 hours left
HB: omg god i know. What are you having tonight?
ME: (pull pen out of your pocket and then hit the feed button on the reciept machine and take a strip of paper. Tear off and look at her either sternly or with a smile whichever works for your style of game and clearly State "your number"
HB: hahaha wow i dont think anyone has done that before. (with huge smile.) whats your name?
ME: Evan Yours?
Me: nice to meet you Natalia
HB: i want to give you my number but i have a bf.
Me: I have a 3 month goldfish
HB: haha what?
ME: were talking about things neither of us care about
HB: omg your funny i like you.
ME: Ill take a vodka soda with lime
HB: Comes back with drink and number on reciept
ME: (BIG SMILE) Thanks
Hb: come back and visit me
One of the guys in our group was a bouncer at the bar and natalia had texted kyle later in the night asking what he knew about me.
I ended up leaving for another bar using the same approach but that bartender had dated one of my buddies friends that was with us in the group so the results were good but i no longer wanted to engage in it.
Hope it works for you