Flirting Advice

So, a woman at work ( who this time isn’t my superior or my subordinate. She is also age appropriate. ) keeps looking to make eye contact with me, and when she does she always smiles. It’s the only time I see her smile while she’s at work.

I’m pretty sure this is flirting. It’s not a fake “just to be nice smile”. It’s not an anxious “I don’t know what I’m supposed to do” smile. It’s more like a really pretty, really enthusiastic full face smile, with kind eyes and stuff, I dunno… she smiles.

So, how do I flirt with this woman?

I chat, I joke, I listen, we laugh. How does one engage in flirting?