How to get a conversation going with a girl I don't know?

[★ D11★]

I have a thing for this girl in my high school, at the end of June she followed me on twitter and I followed her back. For an entire year I have only seen her in the hallway... Over the summer I attempted to talk to her for a bit over Facebook by accidentally sending her a message, I got to know her a bit and she told me a bit about her and we chatted a bit about school and about her country and mine ( She is from Colombia, I am from Brazil). But that ended there. The new school year started and I was hoping I would have a class with her. It didn't happen. But I still see her around in the hallway and I have the same lunch hour that she has. I have noticed that always when I pass by her in the hallway she quickly glances and looks away, I end up doing the same thing. I am not the type of person that goes talking like crazy with anyone, I really feel like approaching her during lunch or when she is in the hallway. But o seem like that guy that is afraid to talk to her in person. I am a bit shy and I have noticed by the most of the time she is around her friends and I don't want to give an akward impression about me. What suggestion can any of you give me? Should I attempt to talk to her again on facebook? Some friends told me to do that, but the conversation I had with her on facebook was brief, and I don't want tway she looks when I look that she is a bit as well... I don't know if she thinks I am attractive or has a thing for me like I have for her, but I want to give it a shot... Help me out please
* Sorry, I typed it too fast... There are some errors. I said I dont want to seem like a guy that is afraid to talk to her in person. And the sentence the end when'''' I say and i dont tway... as well'''' is just messed up ignore that one

[Joshua]

Ou cara, da umas manhas ai pra gatinha! Rsrsrs! Pegador playboy!

Okay, so you talk to her on facebook, so she is already aquainted with you, right? Instead of glancing away from time to time and being shy, go talk to her personally. Send her a message on facebook if you MUST, and then don't send anymore after you have the online conversation, otherwise you will be that random guy she talks to on the internet. Being shy will get you NOWHERE, trust me on this, I've been in your shoes before man, many times before. You want to give it a shot? Then go and talk to her, comment on the latest school activities or something, but a simple "hello" is always good.

Pega ela meu brother! Boa sorte!

[The]

First, you gotta approach her with a warm friendly irresistible smile. If its contagious enough, she will probably smile back and be open to listen to you. Read more here buddy
http://www.tipsgetwomen.com/how-to-talk-to-a-girl/