I don't buy a lot of stuff. I travel instead. I figure spending money on travel is at least offset by saving the carbon emitted by producing and delivering consumer goods. I love to cook, so I don't eat out much. I buy food as little processed as a I can. I buy most of my clothes once a year in a single shopping trip. I consume most of my entertainment electronically (no actual books, etc). I conserve energy and water at home and recycle whenever possible.
I rationalize my travel by living as small as possible the rest of the time. I do try to use transit as much as possible when I travel. I don't buy a lot of things. I avoid single use items, etc.
To be fair, this isn't driven necessarily by carbon consciousness as much as saving money so that I can travel very well on my very modest income.