My wife and I try to minimize our impact on the earth wherever we can, though there's always room for improvement. We've done some big things, such as buying a Prius. It's some of the little things, however, that may have a greater ripple effect and might provide cause for some amusement as well.
Among our pet peeves are the wasteful styrofoam and plastic containers many restaurants use for takeout or leftovers. A while back we decided we would simply bring our own reusable containers with us whenever we went out to eat. We knew this would eliminate our use of throwaway containers. It may be having some other positive benefits as well. Other customers see us doing this and say something like, "Oh, what a good idea!" or "I never thought of that. I'll have to start doing that, too!" The restaurant owners see us doing this and realize their customers are very concerned about the environment; hopefully they'll become more serious about seeking out the most environmentally sensitive products. At our local Indian takeout place, which uses organic ingredients, they laugh when they see us coming. Sometimes they even give us bigger portions!
When it comes to food shopping, we've been buying almost entirely organic for a long time. Lately we've added an emphasis on LOCAL. Knowing it's taking a smaller amount of fossil fuels for the food to reach us is only part of the advantage. There is a wonderful, satisfying (dare I say warm and fuzzy?) feeling when you get to know the person who grew the food you are going to eat. We get this feeling at our local Fairfax farmers market, where we buy strawberries from Russ, greens from Dennis, pies and gallettes from Maria, etc.; at Clark Summit Farm in West Marin, where I buy my incredibly delicious Thanksgiving turkey from Liz; and at the awesome Phoenix Pastificio in Berkeley, where Eric makes the most amazing fresh organic pasta, cut to order, and reciprocates our appreciation of his artistry by practically making us part of his family.
Our local natural food store, The Good Earth, has made shopping local much easier. For years they've posted where each item of fresh produce was grown; recently they've added the mileage from here to there. If your favorite store doesn't yet do this, I suggest you encourage them to do so. Also, I think we can have the greatest impact on people who know us. So we talk to owners of restaurants we frequent, making sure they know we prefer and would be willing to pay more for organic, local ingredients, grass-fed beef, etc.