i can see how dating or hooking up with a coworker could lead to trouble. but if you are interested in someone...
here are some of my thoughts.
i worked at a bakery before and there was a lot of flirting going on between coworkers while at work. We all did our jobs as we did but there were plenty of opportunities to talk to each other. For example while working the cash register, there would be another cashier next to you, and another person making drinks next to you too. When it was slow you could talk and joke around. If you were interested in someone, this was a good time to flirt.
Now you're asking about outside of work. I went out with a couple of my coworkers once to a restaurant/bar. There was a girl who liked me and while there she would flirt with me by touching my arm often while speaking to me. The manager was with us but she didn't really care. I'm certain she noticed. If I was interested in the girl, I could have asked her out on a 1v1. This would have been the right move for me if i were interested.
(I wasn't interested. I actually asked her to stop touching my arm. lol.)
i think you needn't ignore the gal you're interested in. but a 1v1 sounds like the right idea.