First poster nailed it, kinda. Basically stop giving a fuck. It's very liberating, and women are very, very, very attracted to that type of behaviour...Although when people on here say stop giving a fuck, they don't really mean like completely, you can give a fuck, but imagine someone who doesnt give a fuck and act like that, kapeesh?
You don't really have to become a soulless sun of a bitch like many asshole guys out there, you can still care, just don't let anyone know it, lot to say about a caring member of society who is also attractive in that way...
It will be very, very very hard to do at first but you must break yourself from being shy...This is coming from the shyest guy of my graduating class of over 2000...Here is what I did, maybe it can help you:
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Watch this:
http://www.youtube.com/watch?v=mg3m8wRVXWg
"It's only after we've lost everything that we are free to do anything" - Stop being shy, get liberated. DO what makes you shy, approach, approach, approach, and stop being shy!
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Next, go out to the country, a canyon, something....out of earshot from everyone, and get some stuff off your chest, yell at the top of your lungs afftermations like (taken from David DeAngelo and a few others (Had this list on my HD, it was originally posted here)
"I'm confident, comfortable in my own skin"
I'm a good communicator--especially of what I want.
I'm in control and don't let outside events destabilize me.
I'm not needy... I keep my power for me.
I don't need this and can walk away at any time
I think sex is great and have no hang-ups.
I'm comfortable around women.
I can control myself and can wait patiently.
I don't tolerate disrespect of myself, my time, or my property.
I'm a catch.
I'm not impressed by outward symbols, such as money or status.
I may be smitten by a woman, but I don't tell her early on, and I don't let it 'slip' indirectly.
I don't let women use their looks or sexual power to take advantage of me. I give them no special privileges.
I'm not self-conscious and could care less what others think about me.
I put myself and my life first.
I deserve and can hold an exceptional woman.
I am indifferent to the outcome.
I understand the culture, and I 'get it' -cosmo, MTV, style, food, music, humor, etc.
I can deal with any test a woman throws at me... in fact, it's usually kind of cute.
I live in my reality, and you're a guest.
I'm a cause in the world, not an effect.
I make things happen.
Whatever it is, I can deal with it. I do not whine or complain.
I am a leader and when I express my ideas, I don't need anyone's approval, I'm just describing my reality
Never lose your composure. Never get upset.
I have the total indifference to disconnect immediately
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Read PUA stuff - Doesnt matter what system just choose one and go with it, can't go wrong with any of the orriginal stuff, I love David DeAngelo, AFC Adam, and Magic Bullets.
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Spend ATELAST hour a day working on yourself. Including working out, reading PUA stuff, ect...
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This is a good start, but first you must want to change, good luck!