Glass jars with twist off lids can be reused for leftovers and/or fermentation products.
Shop at the local farmer's market.
Do you have a yard big enough to garden? Garden!
Solar panels on the roof.
Catch rainwater to use in the garden. If you have money to spend, that rainwater and house gray water can also be used to flush toilets etc.
Really insulate your home.
Do your shopping by bike whenever possible.
Buy used.