LOL!
This thread has been pretty funny so far. And Spike, those pickup lines were hilarious! Thanks. I haven't laughed like that in a while.
Seriously, I don't think there is anything wrong with a guy saying hi. Although hi is more ambiguous than one of those blatant pick-up lines....LOL....but it shows a friendly attitude and you are wholesomely letting the girl know that you noticed her.
Another good thing is getting into a topic of interest. Not all girls want to talk only about themselves and their lives. If you ask them about their interests and topics they feel strongly about, it can spark a fascinating conversation. Although there has to be something to make a person bring up that topic in the first place.
For example, in my freshman year of college, one of my classmates got my attention by asking about the necklace I was wearing. I love ancient Egypt, so I was wearing a Nefertiti pendant, and it turns out that he was from Sudan, right below Egypt, so he naturally had a taste for things Egyptian. This set off some interesting conversations between us. It's nice to have intellectual rapport with someone, even if nothing more comes out of it than that.
Here is something that may sound strange, with some women it may not work....but if you find a woman attractive, just be honest with her. It may not always be the best way to go about it, but there is something refreshing about it. If you go up to a woman and say something like, "Hello, I don't mean to bother you, but I just noticed you when you came in and I think you are very beautiful." It often takes a woman by surprise because she is not used to such frankness. Some may be pleased by it, others may be turned off, and some may be just plain scared. There have been a few times when guys have just walked up and told me I was pretty, and I found it very sweet and flattering, so I smiled and thanked them for the nice comment. Unfortunately for them, nothing more came out of it than that, since none of them happened to attract me in the same way, but they got me to notice them, and I will always remember their kindness and their honesty.
Sometimes if you tell them they resemble a certain celebrity, that can go either way...positive or negative. When I was in a nightclub watching my brother play with his band, this pretty young brunette kind of bewildered me by telling me I was "cute" and that I looked like Traci Lords. I smiled and said thanks, but I was a little worried, considering that Ms. Lords is a former porn star. Plus this chick must have been bisexual because she kept touching me and playing with my hair. Go figure.
"You look like Pamela Anderson" --- probably a BAD comparison to make (she will think she looks like a slut)
"You look like Michelle Pfeiffer" ---
most likely GOOD (you are letting her know she is sexy in a sophisticated way)
Hope that helps.