How do I flirt with a guy at work as someone who has never flirted?

Basically like the title said, I like this guy at work and can’t tell if he likes me back. Originally, it was me initiating the conversations but now he initiates them sometimes. But whenever we speak, he always maintain eye contact and laughs at what I say (even though I don’t think I’m that funny but okay). He’s also started initiating jokes with me and speaking more. I’ve caught him staring at me a few times whenever I talk to my other male colleagues (who are getting married btw) like at a work’s night out last week, he basically ignored me the entire night and didn't really speak. But when we were in the bar, he was staring at me when I was laughing with a male colleague. So I just want to know how to flirt to figure out if he is actually interested or not.