Pack a waste-free lunch.
Eliminate plastic bags, plastic utensils, disposable containers, paper napkins and those brown bags. Instead use a lunchbox, reusable drink container, cloth napkin and silverware. Find odd pieces of used silverware at a second-hand store so you don't lose parts of your good set. Sandwiches, fresh fruit, vegetables and treats packaged in reusable containers are healthy alternatives to cafeteria and prepackaged foods. They can also be bought in larger quantities, saving money and packaging.

You could save $250 a year and a pile of waste that weighs as much as the average 9-year-old.

Skip canned fruits and veggies.
Whenever possible, limit purchases of canned fruit and vegetables and substitute fresh. The process involved in canning fruit is at least 10 times more energy intensive than picking fresh fruit. If every U.S. household replaced just one pound of canned or jarred fruit with one pound of fresh fruit during each of the three summer months, the total energy saved could operate the kitchen appliances of over 21,000 households for an entire year.

When in season, fresh vegetables can also cost less than canned or frozen.

Paper or plastic? Neither.
Use reusable cloth or canvas bags. The hard part is remembering to take them with you. But they are sturdier and carry a heck of a lot more stuff, saving you energy in trips from the car to the house, plus the bonus of a little upper-body workout. Have a couple of sets and leave one in your vehicle at all times. Paper may be slightly better than plastic because it holds more per bag, but baggers also frequently double bag. Paper bags can be easily reused in many forms and have a better chance of being recycled. If you happen to get a few plastic bags, reuse them as much as possible until they can be used no more. Small trash can liners, doggie waste bags, take lunch to work in them, cover your hair should you get caught in the rain. Keep one bunched up in your handbag for those impromptu purchases.

Some grocery store chains will actually give you credit for each bag you bring of your own, whether it's plastic or cloth.

Skip the treadmill.
If the weather's right, consider giving the treadmill a rest and taking your walking or jogging routine outdoors.

A 25 percent shift in time on the treadmill to time outside would conserve about 60 kWh of energy per year.

Donate clothing and household goods.
Donate clothing and household goods to the environmental nonprofit of your choice. Many charitable groups, including those dedicated to saving the planet, will take such gifts.

Reference:
http://www.bankrate.com/brm/news/energy-environment-2007/tips_environmental_main_a1.asp