Don't bother if you are broiling, roasting or baking a dish that will cook for an hour or more. Don't preheat for more than 10 minutes for breads and cakes. And when roasting meats or baking casseroles, turn off the oven 10 minutes to 15 minutes before cooking time runs out; food will continue to cook without using the extra electricity.
By reducing the time your oven is on by one hour per year, you'll save an average of 2 kWh of energy. If 30 percent of U.S. households did this, 60 million kWh of energy could be saved.