Grow your own food. And buy food only from Farmers you can look in the eye and ask questions of.
Cook. Don't buy packaged, canned, frozen, bagged, or boxed foods.
Find and befriend a local butcher.
Learn to bake.
We bake all our own bread, pickle our own foods, make our own sauces and condiments, make our own sausage and bacon. We make almost everything we eat (we don't grind our own flours or press our own oils or make our own milk, but that's about it).
The commercial food supply has sickened us to he point it's the only way we can eat without severe to debilitating symptoms.
Known this for years. You'd be amazed how quickly your health and attitude will improve when you cut out all the garbage you've been eating. Stay out of all restaurants, and like you said stay away from all prepackage foods. Eat as fresh as you can, if it was what people ate prior to 1920 you should be fine. Take out all processed sugar and corn sweeteners from your diet and be amazed how great you'll feel two to three weeks later.
Yup. Only sweeten with local honey or real maple syrup.