Part of the fun is that there is no general formula to know.
It's pretty much like fishing. You'll never know if you're using the right type of lure, throwing, weigth, until it's pretty obvious some fish is already stuck to your hook.
But, to catch some fish you gotta hit the water. You have to expose yourself. Gotta learn how to be nice to women (assuming you're into them). In general, women like men that are fun, make them laugh expontaneously and seem to be trustworthy. Having a good appearance helps, even more for short term stuff. They then to value things like self care more than looks for the long run, though.
Being a fast answerer may be the key sometimes. A few weeks ago, there is this *extremely* hot chick from the gym which I sometimes exchange some words. Once I heard her and another girl talking something like "when are we meeting for the breeding?" (not in english, though. Sounded more suggestive, or kinky, in portuguese). That felt weird in my ears and I simply stood there with a face. They both laughed, and then she explained me that they were talking about dogs. She'd soon tell me that it couldn't be anything involving her, because "I haven't done anything like that lately". THAT drew my attention. Why the hell would she say that? We barely knew each other. Whatever her reasons were, THAT was the exact moment that a good phrase could extract a good laugh AND maybe - it's always maybes - put me closer to her, and start climbing from there. She's single, it could happen... But I just laughed and played along. Because I'm married. Even though I love my wife, I must say that she isn't as half as hot as this girl - if such a measure can be taken.
But, when I was younger, I used to be somewhat popular with girls, in times where having sex was something hard to happen and, when alone with a girl, we'd usually just trade kiss, sometimes touch each other. I usually got involved with girls already on my social circle. We talked, exchanged some laughs, and soon we'd be together. Sometimes, some girls would approach me, making obvious what their intents were, but... even though that's good for the ego, those weren't the most fun situations. The flirting has some magic that you discover as it unfolds.
I only tried approaching a woman seriously once, in my entire life. I felt that she was interesting from the very first time I saw her. Took me a few days to get the courage to talk to her. It was extremely awkward, but we became friends... then we moved to another cities and kept contact only thru the internet. The years passed and, well, we're married now. I know it's hard to believe. I don't even know why I'm telling this.