Info: I'm 18, I work in the local mall at a shoe store and I'm just an associate

So yesterday I had a blonde come in she was about 16 or 17. She complimented me and I sort of ignore it and did what I normally do. I told her that the shoes she was trying on looked good on her etc. (insert bullshit compliment here). Every time I did compliment her she blushed, I picked up on it quick. When she left my boss had noticed too and told me about it. I WOULD have asked for her number but her mom was with her and its unprofessional. But this tends to happen a lot. It happened again hours later into my shift except this girl was with her dad and her sister.

Question: How do I flirt at the work place at all without getting fucked by the parent or my boss? Should I do it at all in the first place?