Saving money whilst cooking

Energy bills are increasing at the moment so we could need to reduce spending on how much fuel we use, especially in cooking.

I read a book many years ago which gave advice on how to cook whilst using reduced energy. 

The key point I can remember was that the author suggested not pre-heating ovens when cooking and just starting the cooking process from cold.

What other methods of saving energy during cooking can you employ?

Use microwave cooking if you can, plus try the combination oven setting on the microwave.

Look at buying a halogen oven which can help you save energy when you are cooking.

Think about using a slow cooker to cook stews, soups, casseroles, etc. 

Cook several items at once in your oven to save on energy usage. 

Don't overfill your kettle when you are needing to boil water.

Use ambient temperature to defrost foods that you have removed from the freezer rather than using the defrost setting on your microwave.

Check the energy settings on whatever electrical appliances you use, such as fridges, freezers, cookers, etc.

Use vegetable steamers to cook your vegetables, which will help save money.