One established tip is to have soup with your meal, and you'll likely eat fewer calories. Cream soups are exempt from this, however. I just made a fresh pot of Chinese vegetable soup with chicken, tofu, peppers, onion, garlic and bok choy.
Eating throughout the day is a tip that keeps your blood sugar on an even keel, and people who do this tend to weigh less. I have a friend who eats all day, carbs even, and he's pretty thin.
I keep a lot of fresh vegetables and salady things in the house.