Buy things in bulk to avoid unnecessary packaging. Use cloth bags instead of the plastic ones provided.
Write down the codes for your items. On your hand, on paper, or in your phone.
Choose naked produce when possible
Use cloth or mesh produce bags to avoid plastic
Refill liquids like olive oil, honey, syrup, or peanut butter
When refilling jars, always have the rare weight written down for the cashier
You can even find spices in bulk and refill spice bottles you already have