I've never walked up to a single woman at a bar. However, when I was single, I went to a hotel with a band and dance floor in Indianapolis. On the night before the 500, I had 2 guys stop me:
Them: "We've been watching you."
Me: "I'm not that kind."
Them: "No, you've danced with nearly every woman here. How do you do it?"
Me: "The women next to the wall watching the men are here to be picked up. The ones close to the dance floor watching the dancers are here to dance. I ask them."
Moral: Men just need to pay attention. Most don't.