Once you make a list, try to stick to it. Pick up exactly what you need in the amounts you need. If you want fresh ingredients in smaller amounts, check out local farmers markets, or buy from bulk bins.
Some handy free apps to create your shopping lists:
1. Shop smart. Shop efficient.
Once a week have a "Use it up" day, where you look through your cupboards and fridge for ingredients that soon go bad, and create your daily meals based on what you have left. You can do this with your freezer, too! Plan on eating up all that frozen stuff before it gets too old for a cheap meal week.
2. Use up leftovers.
3. Keep those scraps and cutoffs.
4. Take inventory.
5. Understand storage and expiration.
As a consumer, most of these expiration dates can be considered guidelines. Food doesn't know it should be expired on certain dates, and you should throw it out immediately if it becomes self-aware.
Generally, if a food looks and smells fine, then it probably is, but in case you want to know how long certain food products can be stored safely, here is a wonderful chart by Visually.