I work retail. I have to greet every girl that walks in the store, start a conversation, find out what they are looking for, and sell them hella shit. But sometimes I am genuinely interested. So I have a couple of questions, but any strategies or suggestions would be great.

A) I've always heard "you don't shit where you eat," meaning don't get with coworkers, but does this apply with customers too?

B) How can I tell if a girl is legit into me or just being friendly because they feel like they have to?

C) How can I project to the girl that I am actually interested instead of just building a sale?

D) Would a girl be creeped out if I asked for their number on the clock?

For reference, I am a youngster (17) but confident, good looking, tall, smart, pretty awesome. A couple of girls have given me their number at work, but I didn't ask.