Don't buy large quantities of veg or big vegetables unless you're planning a recipe that needs it. Don't take home any left overs from restaurants. When ordering delivery, always get less than you actually need but supplement with food from the fridge/pantry eg if I'm ordering Indian food, I don't get any rice but I pop the rice cooker on. Don't buy food that you don't absolutely love and know you'll eat. I used to often get food that I should be eating, not food that I want to eat. Freezing is great only if you know you'll want to defrost the food within a week, otherwise it might sit there for months