Here are few ideas on saving money while shopping for groceries
Don't be brand loyal use different brands. You don't have to buy generic either. We almost exclusively buy brand names. Buying a particular brand on one or two items is fine. To save the most, get the best deal on the majority of the items bought.
Check expiration dates. Some sale items have dates soon to expire. It isn't a good deal if the date goes out before it can be used.
Don't buy something you don't normally use just because you have a coupon. Using coupons wisely saves money. If you can't or won't use the item, it's not a deal no matter what the price. Some coupons are for new food items. You won't know the "normal or sale" price on these items because they are new.
Match your weekly menu to reflect what's in season and what's in your pantry. If you have to go back to the grocery to get one more item, you'll more likely to buy at a higher price. If it's out of season it will cost more.
Don't buy convenience foods unnecessarily. Convenience costs more. I would never suggest forgoing use of convenience foods. However buying fewer or buying only on sale will save a lot of money. Consider learning how to create your own convenience foods. Many sites have recipes for such food items.