Educate Yourself About the Life of Your Grocery Items
Know how long each of your grocery items will last. For those without an expiration date, there is a handy list on Ziploc's website that gives an estimate of how long different types of produce and meats last when refrigerated and frozen.
Don't wait until the food spoils and you end up throwing it away. Keep in mind the life of each item and eat it based on which one perishes the fastest.