How can you ask your waiter or waitress on a date?
First rule of thumb is to be respectful. Do not look your server up and down and whisper with your friends. Do not use pathetic pick up lines like 'Your name must be Sunshine, 'cause you just lit up my life.' Do not 'hit' on your server ever. If you are serious about getting together with your server or just want to let them know you find them attractive, be sincere and as un-creepy as you know how. You might wait until your server drops off the check or seems to have a moment to speak with you and begin with something like this, 'I don't mean to be rude, but I find you very attractive and I was wondering if you were seeing anybody?' or 'My friends and I are going to this great club later, you should stop by when you get off of work.' If they say no, don't get weird. Just say, 'Thanks for the service, I had a great time.' That way you don't have to feel like an idiot if you ever return.
Avoid asking other employees about the guy/gal you like or sending flowers or gifts to their job. Many restaurants look poorly on this and you may be putting their job at risk. Plus, it's creepy. It can be done but must be done with tact or you will come off looking like an idiot.