Sticking to your grocery list will help you resist expensive convenience and snack foods that may offer little nutritional value. Shop alone and when you aren't hungry, if possible. Shopping with children or other adults usually increases the grocery bill, especially if THEY aren't shopping from a list. Right now, apples, melons, sweet corn and squashes are good buys. Some foods that almost always are low-priced are carrots, potatoes and cabbage.
Many coupons are for name-brand snack foods with little nutritional value.
Spending that money on fresh fruits may be a better health bargain. When you buy deli items, you are paying for someone else to prepare that food. Instead, make your own convenience foods by cooking in double batches. Eat one batch and freeze the other for a night when you just don't have the time or energy to cook. Rather than cooking a roast and serving it as leftovers for several meals, plan different dishes.