General cooking tips
Buy Local Food : See if you can find out where your food has gone before it gets to your plate. You may be suprised by the results. Often it will make financial sense for companies to transport food enourmous distances by planes, boats and lorries. This dosn't take the environmental cost into account (which of course is likely to lead to greatly increased economic costs in the long term).
Oven Tips : If you don't have one, consider buying a self-cleaning oven. They use less energy for normal cooking because of higher insulation levels. They also save on your rubber glove and cleanser purchases! However, if you use the self-cleaning feature more than once a month, you'll end up using more energy than you saved. When you clean the oven, do it right after cooking to take advantage of residual heat.