The amount of success you can have by doing this is staggering. Simply by saying something to a girl (particularly during the day), letting her respond, then eventually saying something else so she knows you want to continue talking to her can lead to great chemistry. Think girls you're standing by, or sitting next to. You don't have to be a seduction master, everyone wants to meet cool people and make friends. Grab her phone number if you want and then continue from there.

I think this is something that gets lost in the pickup community a lot, but if you're just a normal human being with a decent amount of social awareness you'll go far, not just with women.