Girls, Is she interested or playing hard to get? What should I do next?

[Jane]

So I work at the local drug store and this girl came in with her family on a monday about 2 weeks before christmas. They made greeting cards and I made eye contact with the oldest girl a few times and smiled. Well that following friday i was working the registers and she came in and bought nail polish. She wasn't looking at me the whole time she was in line but when she got to the front she kept whipping her hair and running her fingers through her hair with a huge smile. (I dont know if she is just a bubbly person or if its flirting). She left and came in that same day about an hour and a half later with a boy! It was exam week and they bought a poster board...school partners hopefully. She walked in and said "Im back again" then she totally ignored the boy while they were checking out and just talked to me. Well I had not seen her for while but a girl I work with plays soccer with her. She said hi to her while they were making cards and I was right there too. My coworker told me her name and I looked her up on facebook and sent a friend request about 2 weeks after the day she came in twice. Well nearly 3 weeks went by and I havnt seen her come into the store and I thought maybe she was creeped out or something. Well about a week ago, she accepted the friend ship request on facebook! but now I do not know what to do!! Should I send a message to her? Chat? or wait till she comes into the store?? Thanks for the advice