How to know if SHE likes me?

she is new in Theres this girl thats new at school and im kinda interested in her. She doesnt know me but she has seen me in the hallways and on recess. I want to get her phone number and e mail. Please I need some help or advice. I think maybe first i should start a small conversation. She has noticed me looking her in the eyes and we have made eye contact like for 2 seconds, and she quikly turns away. Is that a signal that maybe she may be interested in me? How should I aproach to her when she is alone?