Saying no to the plastic bag, or looking for the least packaged items is a good starting point. If you feel a product has too much packaging or has non-recyclable packaging you could post the problematic packaging back to the manufacturer with a letter of explanation – it might nudge them to respond. For a lot of food items you can shop at the increasing number of refill shops where you can take in your own containers or use paper bags or make use of a milk delivery service. Milk and More for example delivers not just dairy milk in refill bottles but also oat milk, laundry and washing liquids, fruit juices etc.
For more information- https://greentau.org/2022/01/24/the-green-tau-issue-31/