Wash your clothes in cold water using cold-water detergents whenever possible.
Wash and dry full loads. If you are washing a small load, use the appropriate water-level setting.
Dry towels and heavier cottons in a separate load from lighter-weight clothes.
Don't over-dry your clothes. If your machine has a moisture sensor, use it.
Clean the lint filter in the dryer after every load to improve air circulation.
Use the cool-down cycle to allow the clothes to finish drying with the residual heat in the dryer.
Periodically inspect your dryer vent to ensure it is not blocked. This will save energy and may prevent a fire. Manufacturers recommend using rigid venting material, not plastic vents that may collapse and cause blockages.