Read everything that you can.
Study and learn as much as possible. Nerds are very knowledgeable people that can spit off useless facts off the tops of their heads with no problem. Girls think this is sexy because it shows you are smart. A woman respects a man that is intelligent. Nerds are sexy because they give a sense of security to women.
Use your wide vocabulary.
Have a wide vocabulary and use it appropriately. Don't use it to sound like you are talking down to the woman. You have to use it in a way that makes you seem smart and mysterious. If a woman feels like you are smart, they will want to get to know you more. Too often, nerds talk to a woman the way she talks to them. A woman wants to learn more about YOU. Show her that you have something to teach her.
Be the expert.
A woman respects a man that knows what he is talking about. Again, don't talk down to her, but show her you know what you are talking about and that you want to help her learn to. If you see a girl having trouble with something that you are an expert at, ask her if you can help. Letting her see you in action will turn her on, and she will want to get to know you more.
Being shy is not a bad thing.
But learn to open up your feelings to the woman that you like. When a woman feels like you are opening up just to her and no one else she feels like she can trust you. This is because you opening up to her means that you trust her enough to share your deepest secrets.
Don't be afraid to tell the girl how you feel.
Too often, nerds fall into the friend category because they don't share their feelings. If you like the girl, then tell her and let her know that you think she is beautiful. Make the first move. Go in for a kiss. Don't be scared. If she says NO then back off, but really you wouldn't know if you didn't try.