Do: Choose Fish and Meat Carefully

Meat
A rule of thumb for green eating is to eat low on the food chain: more fruits, vegetables, grains and beans than chickens, cows and hogs. Surprisingly, raising livestock, both in practice and because around the world it involves clear-cutting forests for pasture, is one of the world's largest sources of greenhouse gas emissions. Beyond that, generally the smaller the animal, the less environmentally intensive it is to raise for food; a chicken requires less feed and water than a cow to produce a pound of meat. Delving deeper, choosing humanely raised, organic meats ensures that artificial hormones, antibiotics, toxic pesticides or inhumane conditions aren't a part of your diet.

Fish
For fish, choosing wisely is difficult: Many popular species, like tuna and swordfish tend to be contaminated with mercury, PCBs and other toxic chemicals; some farm-raised species (tilapia and barramundi) tend to be raised sustainably, while others (salmon) tend not to be. Meanwhile, some wild-caught fish are harvested sustainably (wild Alaskan salmon, Arctic char), but a great many (Atlantic cod, bluefin tuna) are not, and overfishing is one of today's most pressing environmental issues. Download Environmental Defense Fund's handy pocket Seafood Selector and keep it in your wallet so you can easily choose the best option at the fish counter.

Related: 8 Safe Pregnancy Fish