How can I tell if customer is being flirty or just nice?

Hello everyone! I have been a server for over a year now and I feel like I need some advice. I can't tell if people who small talk are flirting with me or attracted to me. Of course there are regulars who enjoy chit chatting and they do so with everyone but there is a small population that I can't put my finger on if they are kind of being flirty. Please give me guys your best advice and how to look out for it so I can pull away from the conversation. I am a married woman btw!