Just taking a read through the posts, Kieran really added some good stuff! Let me relay one of my experiences.
I went out to a nightclub one night with my brother and his wife. My brother is just amazing with people in general, and women respond powerfully to him. He urged me to approach two girls who were dancing together, so I did. They basically blew me out of the water for using a canned line they heard before (I swear everybody has read "The Game" by now). There were two options I could have used:
1) Look them in the eye and say "Aww, sweetie. Stop. I shouldn't have used a canned line on you and your friend. I get nervous approaching attractive girls and you two look fun, and I wanted to meet you. But when I get nervous I use a canned line sometimes..."
2) Turn into an asshole and say something rude in return.
Guess which one I picked...

They ended up leaving the dance floor. I felt crappy. I'm a 6'2" guy, and these were scared 22 year old girls. WTF.
The advice I got from my bro was to "put down your weapons and make people feel good to be around you." Had I used #1 - yes one could argue it may be a bit wussish, but it is genuine and would have gotten a hell of a better response. Using #2 - I felt bad and didn't get what I wanted.
Ultimate we should ask ourselves - WHAT DO I REALLY WANT HERE?!? If my goal was to make women feel bad, #2 is the way to go. But I never approach a woman to make her feel bad. I have a heart. And I approach women because I'm attracted to them and want to meet them. And what I really want is my target to respond positively to me. So how can I achieve that, in
that situation, for
that woman?!? If she is a supermodel, and everybody tells her she is beautiful, well telling her she is beautiful will not be the way to get her attention. Complimenting her sense of style, or asking about where she got that ring, or anything else unique about her will get a warmer response.
If she is a 6 or 7, an is not used to getting compliments about her looks, telling her she looks stunning tonight will get you results, but only say that if you believe it! Women see through fake compliments.
Fast forward three weeks later, I consciously make the decision that my goal is simply to have fun that night. That's all. And having fun for me means dropping all expectations and limitations on myself. I busted on the hot bartender, and my female friend and I were having a riot about it. The cute girl beside me noticed, and all I said was "Hi!" after making eye contact with her. I asked her about her jewelry, and we got to talking about our ethnic backgrounds. Honestly I didn't even try to pick her up. 20 minutes later we were making out throughout the club. Couldn't f-close her, but #-close instead. Had a fantastic night, and it wasn't just because I hooked up with a hot chick! I had a fantastic night because I made sure everybody else had fun around me.
When you go out - make the goal of the night to have fun. Don't make it to "pick up girls". It will reflect in your approaches.