Beef and pork have the highest ecological costs, chicken and dairy products less so, grain and fruits and vegetables still less. Buy certified organic produce, which is getting easier and cheaper to do as the organic market grows. Organic farming saves huge amounts of pesticides and water pollution. If you also want to save the transport of your food, plus money, plus get good exercise and much pleasure, grow your own. Don't buy more house than you need.
Smaller homes use less material, cost less to heat and cool and light, store less junk.
Every bit of material, warmth, cool, light, and junk comes from the planet, flows to you in a trail of pollution, and eventually goes back to the planet as waste. Upgrade your heating and hot-water efficiency. Get the most efficient appliances and lights. Almost every item on this list not only helps the environment, it also saves money and time and health. Really, the only problem with following UCS's advice is that, if you believe the advertisers, it won't make you admirable, beautiful, ever-young, sexy, powerful, or superior to your neighbors.