Generic rules if you're going to try to ask a cute waitress
Remember that she's getting paid to be nice to customers. Remember also that she might be unusually nice, or even flirtatious, with customers in an effort to increase her gratuity. Watch what she does with other customers (both male and female), and compare. If she's the same or almost the same with everyone, then it's either her normal personality, or she's playing the part.
If she does seem to like you, at least try to get on good enough terms that if and when you do ask her out she is comfortable with you. You probably don't want to walk in, see the waitress, and immediately ask her out.
If you ask her out, do it in a public place (the resturaunt is fine), and try to schedule the date for a public place. You wouldn't believe the freaks that these girls run into, mainly those people who don't understand the first rule. Even if she hasn't run into that kind of person, the perception might exist anyway, which would cause her to be overly paranoid.
Try to vamp her just a little bit before asking her out. For example, you might want to bring her boyfriend up in casual, random conversation one day. If it turns out that she doesn't have one, wait a few days then ask her out. If you did it right, she took the original question/whatever as random meaningless conversation and might not even remember.
I'd suggest against giving her obscenely large gratuities/tips. Give her a normal one, maybe slightly over. You don't want her to think that you were trying to buy her, or that you think that by giving her large tips she owes you something. (A recent real life reference is a British doctor(?) who went to some strip club in New England, ran into a waitress who was working her way through college, and cut her a check for $10,000 to pay for the remainder of her schooling...then asked her out. She declined.)
Unless you're God's gift to women, you probably don't want to ask her out in a situation where she feels compelled to answer one way or the other, such as in front of a horde of coworkers.
Respect the cute waitress. From what I've seen, they don't get a lot of it from most people. (This is a regional thing, I'm sure.)
And finally, remember that, particularly if said waitress is in her late teens or early twenties, she's probably trying to work her way through school. This goes back to the point above.
If it's at a place like Hooters, you might not want to bother. From speaking with a couple female friends I know who work in that chain of sex-oriented resturaunts, I can tell you that most of the girls there hate their jobs, can't hold a whole lot of respect for the people who go there, but love the money. The money is why they're there. ($150 for a 6 hour shift, for example.)