"Get out of the supermarket whenever you can."
You won't find processed food products at the farmer's market. No high fructose corn syrup, no packages with long ingredient lists, nothing microwaveable, and nothing old from far away. All you'll find are fresh, whole foods, harvested at the peak of their taste and nutritional quality.
All the tips given for the 28 Days of Real Food Challenge were compiled from "Food Rules", by Michael Pollan.