In fact, some -- like resolving to be a truly eco-conscious eater -- are best undertaken during the summer, when fresh food is everywhere. There are a ton of little things you can do that have a huge impact: turning on the oven less often, making delicious use of every last part of a pasture-raised chicken, stocking up on seasonal berries for winter. And, of course, there's the power you wield with your grocery cart.

"If 40 percent of American households bought only organic milk, it would change dairy production," says Michel Nischan, co-owner of the Dressing Room restaurant in Westport, Connecticut, and author of "Sustainably Delicious." "You really can be a hero one product at a time."

What follows are fresh ways to shop, cook, and eat heroically, now and all year round.

The stems of cauliflower or broccoli, the inner leaves of celery, the fronds of fennel, the greens of beets, even the stems of herbs: all edible, all tasty.

Forgo bagged and boxed salad greens for loose bunches, and look for anything with the roots attached. You'll use zero packaging, and you can compost -- or maybe even eat -- the stems.

Your purchases will directly support local agriculture. There are now more than 5,200 farmers' markets in the country (find one near you at localharvest.org), and the numbers will continue to grow if we make them our personal Stop & Shops.

Get staples. Instead of only a handful of tomatoes, pick up onions, potatoes, and herbs.

Buy heirloom. It's not just a boutique marketing term. It describes vegetables, fruits, grains, and beans from seeds that have been passed down for generations, grown in small crops that may restore the health of the soil.

Stock up. Buy in bulk when produce is in season. Freeze it, pickle it , or preserve it, so you can still eat local when you have off-season cravings.

Get advice. Ask the farmers for recipe suggestions.

Challenge yourself. Try to use only what's at the market for a week's worth of meals.

"Local is always the priority, but the organic label really does mean something," says chef and author Alice Waters. "If you can't buy local, buy organic -- coffees, teas, jams, olive oils, honey, nuts, raisins, oatmeal, beans, grains. There's so much available across the country now."

Purchase them at a farmers' market, directly from the person who collected them. Keep in mind a cage-free label in the grocery store doesn't necessarily mean the eggs came from chickens that were running around a yard -- they still could have been raised indoors.

Hardy root vegetables like squash, sweet potatoes, beets, turnips, and rutabagas will keep four to six months in a chilly cellar where the temperature stays 40 degrees or below. Store them as close to the time they were harvested as possible -- preferably unwashed, green tops still attached, and packed in sawdust or moist peat moss.

Find a community-supported agriculture (CSA) farm near you at eatwellguide.org or localharvest.org and pay a subscription fee for regular batches of local produce (and, in some places, grass-fed meat). If you're worried about being able to use it all up, go in on it with a friend or two.

"If you're buying food at the store, try to choose products that come in the least amount of packaging possible, or in containers that are easily recyclable in your area," suggests Alexandra Zissu, author of "The Conscious Kitchen."

Until the USDA revised the standards last year, 30 to 40 percent of the milk sold in the U.S. that was labeled organic was actually from factory farm-raised cows. Regulations are tighter now, but not all organic milks are created equal. Check your brand at sustainabletable.org -- and opt for antibiotic- and rBGH-free (no artificial bovine growth hormones).

Anything that qualifies as a whole (i.e., unrefined) grain -- brown rice, barley, farro, quinoa -- is automatically healthier for you and the environment than a processed grain like white rice. Even better is buckwheat, which can improve soil quality.

You'll cut the cooking time -- and energy usage -- in half.

"My criteria for choosing packaged foods are: nothing with more than five ingredients, no ingredients I can't pronounce, nothing artificial, and no cartoons on the package," says Marion Nestle, nutritionist, author of "What to Eat" and creator of Foodpolitics.com. 

"Why no cartoons? Because those companies are deliberately marketing to children, and I want to discourage that."

They top the list of foods to buy organic because of typically high pesticide levels. Stock up when they're available locally, spread them on a cookie sheet, and freeze them for six to eight hours. Then transfer to storage bags or containers. They're great for making smoothies, desserts, or just for snacking, even when summer's only a distant memory.

Carbonation machines keep bottles out of the landfill. Mix seltzer with a fresh fruit syrup to make fizzy drinks. (Heat 1/3 cup sugar and 1/3 cup water until sugar dissolves. Add 1/2 cup raspberries, remove from heat, let steep for 30 minutes, then strain. Add to seltzer.)

Shop at your neighborhood bakery or farmers' market. You'll eliminate a plastic package and a fuel-burning journey, and the bread's likelier to be made with fewer ingredients.

Whiz stale bread into crumbs and freeze. Or dice and toss with olive oil, season, and toast to make croutons.

If the number on the produce sticker at the supermarket starts with 9, then the item is organic.

"Become friends with your local growers and fishermen, so you can keep in touch about what's just been picked or caught," suggests Martha Stewart, founder of Whole Living's parent company.

Avoid buying items with corn or corn-based substances (corn oil, cornstarch, or corn syrup) as ingredients. According to the USDA, at least 85 percent of the corn grown in this country has been genetically modified, meaning the plants were altered to make them more pest resistant. The Food Alliance Certified seal, at left, means that a product has not been genetically modified. 

Fresh corn is easy to stockpile. Blanch the cobs, strip the kernels -- OXO's Corn Peeler works as effortlessly as a potato peeler -- and freeze.

Instead of running greens under the faucet for minutes at a time, submerge them in water, drain, and roll in a cloth towel. Rinse only if they're still gritty.

Repurpose the nutrient-rich water you used to blanch a batch of vegetables for soups or for boiling pasta. (Or water plants with it if unsalted and oil-free.)

You can enjoy the varieties below with a clean conscience, says Barry Estabrook, writer and founder of Politicsoftheplate.com. For on-the-spot ratings, text the Blue Ocean Institute's FishPhone -- 30644 -- with the message "fish" and the kind you're planning to buy.

Wild Alaskan salmon, Alaskan halibut, or just about any fish from Alaska: "The state has some of the most environmentally sound fishing practices in the country."

Anything in a shell: "Mussels, clams, and oysters are almost always sustainably raised."

Wild American shrimp: "The tiny ones from Maine, pink shrimp from the northwest, and wild-caught from the Atlantic."

Local varieties: "Dungeness crabs from the Northwest, line-caught striped bass and haddock from the Northeast, and so on."

American albacore is the only canned variety out there that's certified to be sustainably fished. Wild Planet's albacore is hand-packed in BPA-free cans without added oil, water, or fillers. From $4 a can; wildplanetfoods.com

Once you've used up the last of a chicken or a turkey, throw the carcass in a stockpot with enough water to cover, a whole or half onion, a carrot, a celery stalk, a few garlic cloves, and a couple of sprigs of herbs like parsley and thyme. Simmer (uncovered) for at least two hours, occasionally skimming the foam that forms at the top. Strain it, pour into glass jars (leaving room for the liquid to expand), let cool, and then freeze. 

You'll have four or five quarts of ready-made stock on hand for soup, braised meat and vegetables, pan sauces, pasta, and risotto. You can use this method for vegetable stock too. Start a collection of unused vegetables -- an onion quarter, carrot greens, a turnip, wilted herbs -- and simmer them in water for at least an hour.

You'll get more meat -- and rich stock -- for your money and far less waste. Look for chickens without hormones that were pasture raised. And they couldn't be easier to roast: Brush with butter and season with salt and pepper; bind legs with twine. Roast at 450 degrees, basting occasionally, for about an hour.

As you're roasting a chicken or baking a lasagna, throw in some vegetables or tomatoes for roasting, and maybe a loaf or two of zucchini bread. The goal is to turn the oven on just once or twice a week.

It really is best to skip traditional nonstick pans with carcinogenic chemicals (PTFE and PFOA) in the coating altogether. There are alternatives -- like Cuisinart's GreenGourmet line, which has a nonstick interior that's ceramic rather than petroleum-based. Or keep it simple and cook with pots and pans made from stainless steel, pure cast iron, or enamel-coated cast iron.

Use carbon-neutral Green Hearts Natural Charcoal Briquettes made of wood.

Though rancher Bill Niman says the first step toward a sustainable food system is to eat less meat overall, there are easy ways to be a better meat eater:

Skip the additives. Buy only absolutely antibiotic- and hormone-free meat.

Choose domestic meat. You can imagine how eating lamb from New Zealand might affect your carbon footprint.

Eat it seasonally. There's a reason we have turkey at Thanksgiving -- the birds mature in the fall. Look for lamb in spring and goose around Christmas.

"Almost anybody can grow just a little bit of food," says chef, farmer, and activist Michel Nischan. "You don't have to be an expert gardener."

"A huge amount of water is required to produce regular table sugar," says Louisa Shafia, author of "Lucid Food." "Honey, on the other hand, is a perfectly renewable resource that requires little more than healthy bees and healthy plants and flowers from which to pollinate. Try adapting your favorite recipe to use honey instead of dry sugar."

Not just vegetable scraps and eggshells, but leftovers, coffee grounds, stale bread, tea bags, and pretty much anything else (though animal fats, scraps, and bones don't break down easily and can attract pests). If you can't use it all, give excess back to local farmers or to a community garden.

Plugging in a high-speed blender or a food processor is worthwhile if it motivates you to cook more often and eat more fruits and vegetables. You can get a couple of meals out of a seasonal soup and several out of a homemade pesto.

Your watchwords are "fair-trade certified" and "sustainable." Also look for "bird-friendly" or the Rainforest Alliance label, which means the beans were grown responsibly. Brew it at home with a French press (2 tablespoons coarsely ground coffee per 6 ounces water) and you've started the day on a very green foot.

Most mass-produced olive oil is grown with pesticides, which can be even more concentrated in the oil than on the olives. Budget for domestic (likely California), small-producer olive oil labeled organic.

Salad dressing is a packaged condiment that's so much better homemade -- and it's incredibly easy to whip up. Mix 1 minced shallot, 3 tablespoons any good vinegar, 1 teaspoon Dijon mustard, 1/2 cup olive oil, and salt and pepper. It'll keep for a week in a corked glass bottle in the fridge.

Brands like If You Care produce unbleached paper lined with vegetable wax. Use it instead of aluminum foil or plastic wrap. It's compostable, reusable when wiped down, and can be fastened with masking tape.

Keeping track of which plastics are safer (Nos. 2, 4, 5) and which are more likely to release toxic phthalates, styrene, or BPA when heated or warm (Nos. 3, 6, 7) can be confusing. (We have yet to come up with an easy-to-remember shorthand.) So make it a policy to use as little as possible in the kitchen. A few ideas:

Get Glass Containers... Airtight plastic bags are okay, but the Glasslock containers shown at left are freezable and microwavable.

...And glass bottles and jars. Store liquids like juice, oil, and vinegar, or bulk-bought grains, beans, and nuts.

Wrap with dish towels. Surround baked goods with cloth instead of plastic wrap. You can also use a towel and rubber band to cover bowls of food to chill in the fridge before serving.