How do I let deli guy know I'm interested?

There's a cute cashier at the grocery store I frequent in my town. It has been a LONG time since I dated or even really flirted with anyone and I'm not sure how I'd signal my interest to someone I don't know that well or only in a "professional" setting. Whenever I see him he's always super smiley and friendly. Of course, that could just be him being good at his job. But, he's attractive and seems nice.

Caveat: There's a tiny sliver of leeway in that I know he is an acquaintance (and I mean acquaintance, not best friend or anything) of my brother but he doesn't know who I am or that I'm related to my brother. He knows us separately.

The last thing I want is to come across as a total lunatic when he may well just be doing his job. Maybe I'm reading too much into it, but he has served me a few times now, remembers me, watches me when I come in and brushed my hand once. (ha)

I am probably being crazy, and of course he's working, but what should I do to signal my interest? He's got a killer smile and quite the twinkle in his eyes.:D

Ask him to go out with you. Ask him for his phone number. Say..."I like you, do you want to hang out some time?". Egads people are repressed. Worst case scenario? He's with someone...or he's not interested and says no. Big deal, think of it as a confidence builder...plus you won't have to wonder if he's into you.