Approaching women is not that tough as you think. You just need confidence and should know to use the right words. Here are a few things you should know before approaching the girl you just met and you are attracted to.
 

1. The first most important thing is to take it easy. If you get all jittery and scared and think that if you don't get this girl, it is going to be the end of your life, then you will never really get to know her. So be cool and don't overstep your bounds. If you succeed, its great and if not then move on. Don't care about the outcome so much that it will make you nervous and you will spoil every chance that you ever had.
 

2. Be confident. People show confidence (or lack of it) in a thousand small ways; your posture, the way you talk, a lack of waiver in your voice, eye contact, body position, placement of the hands, etc., etc. All of these are critical and create an impression. Your impression should always be one of confidence.

3. Smile. This is the best part. Your smile can mean a lot. Smiles can easily look like nervousness. Therefore you need to know how good your smile is. You should practice this in front of the mirror until you feel comfortable with it and until it looks natural.
 

4. Take the conversation somewhere. Pickup lines are no good and will take you nowhere. Your conversation should be intelligent and meaningful. That doesn't mean that you start discussing politics or football with her. You're trying to get to know the woman in the quickest, most direct way possible. Thus, get her talking about herself! Use this as a discovery of both who she is, and what you need to do to move the conversation on.

5. Listen to her. This is an important part of the conversation. Just don't keep talking on and on. You need to listen to what she says and focus on her. Look into her eyes.

6. Close. You have to ask for what you want. Don't wait for her to do the thing for you. Far too many men expect the woman to close for them; waiting for her to give you her number. Instead, you need to be the one to ask for it. Then, when you do, be direct, calm, confident, and don't ask her - tell her. Say something like, "Here, write your home phone number down on this paper and I'll call you sometime to continue this conversation."

7. Leave! You always want to be the one to end the conversation. Don't over-stay your welcome. Close, and make your exit.