Just be BOLD. That about sums up the first step of the process. What you say means less than how you say it. Women have some innate radar/x-ray vision that allows them to know within milliseconds if they want to (or will, more importantly) sleep with you. From there it's all about not coming across as needy or stalkerish. It's equally easy to get a girl in bed as it is to scare one off really, but no one can help you with the stalker part. If you are a psycho, it's tough to hide. Women pick up on it.
Just be BOLD and let nature do the work, try not to say anything stupid or weird and you are in like flynn.
Women love attention, they crave it, but they are good at spotting weirdo's so approaching them can be a double edged sword. Dance the right edge and you can't miss.
I think the 2 mistakes guys make are not trying often enough (this leads to chasing the women who have already decided NO is the answer) and trying too hard (this lends itself to the psycho issues as stated earlier).
Here is a question- which is more sad, the man who never tries to get pussy or the man who tries way too hard to get girls that will never sleep with him? Hmm....
