The key is just to recognize what's actually food and what's not. Most of the shit you buy at restaurants and whatnot, is not real food. Its some other sort of crap that may or may not have been formulated from something that was once real food; its high in fat and salt, which tricks your body into thinking its satiated while its really starving for vital nutrients.
Variety is really the key to health. Always aim to eat a staggeringly wide variety of different types of fruits (fresh and dried), nuts, seeds (hemp seeds every day! with every meal and between snacks, I'm not kidding its one of the best things you can do for yourself), veggies, legumes, soy in moderation. Meat can be good in moderation, but not if its factory-farmed. Just be smart and listen attentively to your body-- do what makes you feel best. And drink yerba mate from time to time.
Oh, and one more thing. Avoid artificial sweeteners at ALL COST! They are poison, pure and simple. Any type of sweet "diet" drink is loaded with that toxic garbage. Aspartame, acesulfame potassium, saccharin, sucralose: there is no such thing as safe exposure to these chemicals, consuming them is ruinous to one's body and mind.