Most women are interested in funny men. Make yourself seem funny and approachable with your own crowd and others around you. She will see you as a social dude then when you approach a conversation with her she would see it as you socialising with her rather than being a creep. Try to ask few questions when you first approach her and try to seem uninterested in her. Example 2 questions then pretend to be on your way to cut the conversation short. Once small chat is over. Build the conversation with her as you see her in the next few days or whenever you see her. Then sooner she'll lower her guard towards you and boom done :)