For example, waiters tend to give better service to tables that appear distressed. This seems a little counterintuitive, I know, but I guess it’s their way of making you feel better. I can personally attest to this practice, since the best service I ever had was at an Olive Garden when I was homicidal from a combination of hunger and general irritation. You have never seen so many breadsticks, so fast, and so often. I also drank about six Diet Cokes. Great meal, or greatest meal?
You should also dress well. As in every other aspect of society, looking important goes a long way. It’s a nonverbal way of saying both “I am important enough to wear this outfit” and “I have money enough to afford this outfit.” I’m not advocating for nonstop suit wearing, but maybe leave the college sweatshirt at home.
If you have another engagement afterwards (movie, concert, bank robbery), you might want to casually mention it. The waiter will probably speed up your service so you don’t miss your film/music/felony. If you just want to be served quickly despite having no other activities planned, you could probably just make something up. I suggest going with that “bank robbery” idea.
Granted, many of these conclusions depend on the humanity of your waiters and waitresses. I daresay there are a few who don’t care a lick about how you act or what you’re wearing. This is the beauty of an industry where tips are involved. You as the diner can show how well or poorly your server did, assuming you’re not a stingy bastard who tips in coins or something.