Using the motto "Do as I say and not as I do" has to be one of the most irresponsible parenting tactics on Earth. Not to mention fruitless, because one thing we know is that kids mimic their parents' actions, from simple mannerisms and things we say to more serious choices, like smoking cigarettes.
This means that the responsibility for setting an example with actions is placed squarely on the heads of adults. If you want to teach children about sustainable living, then you have to practice it yourself. Recycling, using less water and power, even the car you drive all send powerful messages to your children. And along the way, be sure to use your words as well as actions to get the message across.