Drink the spinach water.  Another bit of traditional wisdom with good science behind it: The water in which vegetables are cooked is rich in vitamins and other healthful plant chemicals. Save it for soup or add it to sauces.

"Eating what stand on one leg (mushrooms and other plant food) is better than eating what stands on two legs (fowl), which is better than eating what stands on four legs (cows, pigs, and other mammals)." ~ Chinese Proverb

Treat meat as a flavoring or a special occasion food.  "Flexitarians" - people who eat meat a couple times a week are just as healthy as vegetarians, yet healthier than those who eat meat everyday. Consider swapping your 8 oz meat and 4 oz veggie servings (8 oz of veggies/4 oz meat).

Eat mostly plants, especially leaves.  While scientists disagree on what's so good about eating plants (antioxidants? fiber? omega-3 fatty acids?), they do agree that it's really good for you. There are scores of studies showing that a diet that is rich in fruits and veggies reduces the risk of dying from all Western diseases and reduces the risk of cancer. By eating a diet that is primarily plant based, you'll be consuming far fewer calories.

It's not food if it's called by the same name in every language. 

It's not food if it arrived through the window of your car.

If it came from a plant, eat it; if it was made in a plant, don't.

Don't ingest foods made in places where everyone is required to wear a surgical cap.

Eat only foods that have been cooked by humans.  If you are going to let others cook for you, you're much better off if they are other humans, rather than corporations (who use too much salt, fat, sugar, preservatives, colorings, and other biological novelties).