By detaching from the commercial economy as much as possible and instead engage with the local gift economy.

If I must buy, eg. fresh produce, I buy from urban farms and farmers' markets.

If there's something I need at a large store, I try to purchase from someplace that has a commitment to ecological efficiency and reduced packaging (such as Aldi) or is enployee-owned (such as Hy-Vee).

And if there's something I can only get at a big-box store with evil and predatory practices, I do my level best to shoplift a greater value than I purchase, to limit their profit from the interaction.

And of course, by getting there and back on a bicycle rather than in a car.