When you sit down, the waiter will bring your table the accoutrements of a Chinese-American meal: forks, glasses of ice water, a dish of plum sauce, and a bowl of fried chow mein noodles. These are like coffin nails in your hopes of getting authentic Chinese food. Send them back. (Okay, keep the ice water.) Ask for chopsticks and tea. Only barbarians spear their meat with forks; learn how to use chopsticks. And tea has been the traditional accompaniment to Chinese food for over a millennium. (Don't add milk and sugar!) If the restaurant is especially good, the waiters will replace the chow mein noodles with salted peanuts and spicy pickled vegetables to whet your appetite.
Now for the ordering. In Chinese culture, this weighty task is usually given to the host or head of the family. Following the example of the sages, you're to select dishes that honor the cuisine, ingredients, and skills of the chef. If you're in a Cantonese restaurant, avoid ordering a spicy Sichuan specialty like mapo tofu. And if you're in a Sichuan restaurant, don't ask for dishes that aren't greasy and spicy—just go to another kind of restaurant. Stay away from dim sum at dinner, because that's a late morning and lunchtime food. Don't be tempted by the sushi or pad thai noodles on the menu; they're better at Japanese and Thai restaurants. Steer clear also of "healthy" dishes like steamed chicken with broccoli, which were invented to indulge American medical obsessions. Actually, you'll find most of the unhealthy dishes—deep-fried and covered in gloppy sauce, like General Tso's chicken—on the Chinese-American side of the menu.
If you find yourself lost and don't know what to order, look at what the Chinese patrons at the other tables are eating. Ask the waiter to recommend some Chinese—not Chinese-American—dishes. If there are specials written in Chinese characters on the wall, ask for a translation. Consider ordering foods you've never tasted before. The guiding principle of a Chinese meal is balance. The dishes should offer a pleasing variety of seasonally appropriate ingredients (meat, seafood, vegetable, tofu, etc.); cooking methods (stir-fried, red-cooked, steamed, braised, stewed, soups, etc.); flavors (bitter, sour, sweet, pungent, salty); colors; and textures. Some ingredients, like bitter melon or spongy and slimy sea cucumber, may be a bit too strong or weird for American tastes, but that's okay because it's good to push your boundaries.
Finally, enjoy your food communally. A Chinese meal is a social event meant to break down boundaries, not build them. There's nothing sadder in a Chinese restaurant than seeing a table where eaters guard their individual portions of beef with broccoli or sweet and sour pork like inmates in the prison mess hall. There's nothing happier than sitting at a big round table where every diner is eager to try everything. The tea is poured; the waiters cover the table with an array of fragrant, multi-hued dishes; and the chopsticks dart here and there. The lazy Susan revolves as the diners discuss the relative merits of the dishes. A sweet air of contentment settles over all.