As an attractive woman who has been working in the restaurant industry for over five years I have to warn you to proceed here with caution. You don't want to be the guy who asks the girl out when she is working unless you KNOW 110% that she is into you. Otherwise it is just an awkward mess because she is stuck at her hostess station being hit on by a creepy guy who she has to be nice to because she is working. Do you have a friendly rapport built up with her? Does she address you by name? Are you friendly and chatty when you see her? More importantly, is she? Does she recognize you at all when you come in? If the answers to these questions are 'Yes!' then proceed.
If you're feeling confident, and you need to be, then the next time that you're there be friendly but don't monopolize her time and don't make a big deal out of it. As you leave mention that you would like to take her out (something like "I'd like to take you out sometime if you're interested") and hand her a business card or if you don't have a card a simple note with your name and email and phone number on it. Don't be too silly with the note. I used to have the lovelorn notes written on the backs of receipts and cocktail napkins that were left for me by lonely drunken guys magneted to my fridge for my room mates and guests to laugh at. The ones that got the best response were funny, creative or simple.
I have gone on dates both casual and romantic with customers and I've even developed close friendships and romantic relationships with people who I met while working, but if you come at me awkwardly or try to take up my whole night while I am trying to do my job or seem desperate or weird or creepy or wait for me outside of my job until I get off of work it's never going to happen and in the latter example, you might get pepper sprayed.