If you want to save more on food and other grocery items, the best thing to do is to do the following:
Write a list. Check your pantry, cupboard, and your refrigerator and list down the items that you need to buy for a week. To help you with this, it is always best to plan a menu first. You can check your current inventory against the menu and tick off the ones still available in your supplies.
Keep track of how much things cost. You can do this by listing down the prices beside the respective items on the list that you have. Or, you can compare the prices against your grocery receipt after.
You will need it when you next make a list. You can calculate an estimate of how much you would need to bring on your next trip.
Stick to your list and avoid impulse buying. To help do this, know the layout of the grocery so you can just go directly to the appropriate aisles.