A girl...

[Sam]

Hi there I have never been massive with the ladies. I'm not really ugly or fat or anything like that it's just I have never really bothered.

Basically there is this girl that I see for about 10 seconds a day who walks past me when I walk home from school. She always smiles at me and gives a sort of look (if you know what I mean)

She just started doing this so I was going to ask for her number etc...

Tell me if this is a good approach:

Me: Hi there my name is Sam what's yours?
Her: BLAH BLAH nice to meet you...
Me: That's a lovely name, listen I'm not all great with the asking out stuff but I was wandering if you'd like if you want to meet up later? Maybe I could take your number
Her: Yeh sure (hopefully)

I'm not at all nervous around girls and I haven't got much to loose so what do you think?

[J0R63]

Talk a little bit more, and start asking from email, as she will feel more secure. While she's writing you her email, ask for her phone, because without her knowing it she will think inside "If I am giving him my email, there's no point in no giving him my mobile phone" .

[Pink Floyd]

Go for it, turn mutual conversation into actual conversation, actual conversation into things you relate on, etc. You have a good chance of forming a relationship with her.

[Cybr]

I don't think you should introduce yourself in the first sentence, but that's just me. The way I usually do it is:
Me: Hey. (As your about to walk past each other. Make sure to smile)
Girl: Hii. (If she gives a fake smile, just walk away. If she gives a real smile, continue the conversation. Hopefully you can tell the difference.)
Me: I don't think I know your name. (Of course, with a smile)
Girl: Oh, it's [NAME]. I don't think I know yours either.
Me: Hmm, I like that name a lot. I'm [NAME]. We should hang out some time. If you want.

If you get there with no problem, the rest is simple. Hope this helped.

[Pink Floyd]

Never miss doubt "the look". Make yourself known, if she's giving you that look, she probably wants you to introduce yourself. If not, what harm could it do?

[Cybr]

Never miss doubt "the look". Make yourself known, if she's giving you that look, she probably wants you to introduce yourself. If not, what harm could it do?

Exactly. If you don't know her, what do you have to lose? Other than the awkwardness of walking by her every day if it goes wrong.