Everyone is different, but you should make sure you eat healthy foods full of nutritious ingredients. My favourite breakfast before a short run is a bowl of Honey Nut Chex with almond milk. It's light and provides quick carbohydrates to fuel my workout.
For longer runs, I eat half of a bagel with peanut butter and honey. I've always stuck with Clif Shot Bloks for mid-run energy and electrolytes, but once I got into much longer distances, I was getting so hungry. I started adding in half of a Larabar about eight miles in — they offer carbs and protein and are super easy to digest.