I have a few thoughts on this:
Start small – start with something like organic coffee or recycled content toilet paper. Develop habits with these things, then look to expand your green habits.
Focus on repeatable actions (habits) and on major purchases, which usually have the largest impacts.
Alonovo.com is like Amazon.com but it allows you to compare products based on the social and environmental record of the company that makes them. Disclaimer: I work for one of the companies that provides information to Alonovo.
