When going to the grocery store, rather than opting for the plastic bags to collect your produce, bring canvas bags from home so that you can easily reuse them each grocery trip.
You can grow simple herbs at home that don't require a garden. It's also quite rewarding to grow your own food. Try it out with herbs or even produce such as green onions.
If you happen to have paper bags from your shopping adventures, reuse them as trash bags at home, regift them and put presents in them, or take it apart and use it as a book cover or wrapping paper.
Go paperless. There's no reason we should still be receiving paper bills. Opt for paperless billing for your utilities and credit cards.
Of course it's not always possible but try to rely on public transportation or even walk. If your destination is a mile away, it could be great exercise for you!