Waiters share insider secrets about restaurant -- from what days to avoid dining out to how much to tip.1. Avoid eating out on holidays and Saturday nights. The sheer volume of customers guarantees that most kitchens will be pushed beyond their ability to produce a high-quality dish.2. There are almost never any sick days in the restaurant business. A busboy with a kid to support isn't going to stay home and miss out on $100 because he's got strep throat. And these are the people handling your food.3. When customers' dissatisfaction devolves into personal attacks, adulterating food or drink is a convenient way for servers to exact covert vengeance. Waiters can and do spit in people's food.4. Never say "I'm friends with the owner." Restaurant owners don't have friends. This marks you as a clueless poseur the moment you walk in the door.5. Treat others as you want to be treated. (Yes, people need to be reminded of this.)6. Don't snap your fingers to get our attention. Remember, we have shears that cut through bone in the kitchen.7. Don't order meals that aren't on the menu. You're forcing the chef to cook something he doesn't make on a regular basis. If he makes the same entrée 10,000 times a month, the odds are good that the dish will be a home run every time.8. Splitting entrées is okay, but don't ask for water, lemon, and sugar so you can make your own lemonade. What's next, grapes so you can press your own wine?9. If you find a waiter you like, always ask to be seated in his or her section. Tell all your friends so they'll start asking for that server as well. You've just made that waiter look indispensable to the owner. The server will be grateful and take good care of you.10. If you can't afford to leave a tip, you can't afford to eat in the restaurant. Servers could be giving 20 to 40 percent to the busboys, bartenders, maître d', or hostess.11. Always examine the check. Sometimes large parties are unaware that a gratuity has been added to the bill, so they tip on top of it. Waiters "facilitate" this error. It's dishonest, it's wrong-and I did it all the time.12. If you want to hang out, that's fine. But increase the tip to make up for money the server would have made if he or she had had another seating at that table.13. Never, ever come in 15 minutes before closing time. The cooks are tired and will cook your dinner right away. So while you're chitchatting over salads, your entrées will be languishing under the heat lamp while the dishwasher is spraying industrial-strength, carcinogenic cleaning solvents in their immediate vicinity.