My achilles heel

I got no problem in initiating a conversation and closing. However, when it comes to the point of getting further like asking for her number. I kind of getting a mess. I don't really know what to do. Could you help me on this guys?

Come up with a reason for wanting her number. If you really are hooking her and she likes you, it doesn't even have to be a very good reason for the number. Generally you probably started the coversation on a situation Opener. It started a conversation on something you are both interested in. It is only "natural" that you would want to talk to her again about the item, or hang out the next time you go do X in relationship to whatever you were talking about, or maybe she is just "a cool person" which you "Might text in the future".

very good answer.

One example I can give you is about a korean girl that I've met in class. When I first attempted to practice connecting with her, she basically had a huge Bitch Shield and blew me off.

Then, for some odd reason, she became friendly to me on the second class and we went home together. We've carried this great conversation (I was light and funny) and everything was great. When we parted, I said "hey, maybe we should add each other on facebook or something". She agrees.

There's always the "let's setup a study group and exchange contacts so we can get together".

If you're not in a school environment you can even be a bit more direct and say "hey, it'd be cool for us to hangout sometime, why don't you give me your number and we'll hang out."

I agree with what Mystery_wannabe said. Always have a focal point in every direction. Come up with a reason to have her number. There are lots of ways to do that. You may use the lines given by Mystery-wannabe. Stay cool and swift in your action

One thing to note when asking for a number. Never flinch. If you come off looking like you are holding your breath, she won't give you the number most of the time. You want to ask like it is a perfectly natural thing and means nothing to you.

Thanks for the responses guys. I reflect on your advices and practiced it. Yes indeed, it is true that if you wana ask for her number and it seems that you're not so interested about it (in a sense that you badly need it), they seem to give it to you rather than being very serious just asking for a number.