There are two things to save here. One - the cost of the energy used in actually washing your itemsthe cost of the powders or creams and softeners etc and, Two - the cost of the powders or creams and softeners etc.

Do more low temperature washing

You can’t wash materials which are supposed to be in a cool wash in a hot one, but you can wash things normally associated with a hot wash in a cool one.
Most modern Washing Machines being sold now have pretty good ‘environmentally friendly’ specifications and most have a 30 degree wash.
This usually takes only about half an hour to go through the cycle and for most medium wear clothing etc. is ample. Savings on both water and electricity.

Service your Machines

Regular servicing such as clearning out any ‘cloogy’ parts will make your machine more efficient, especially the build up of fluff in a Tumble Dryer.

Wash by Hand

Going back in time ! Harder work maybe, but look at the savings - no electricity atall other than warming the water!

Do less washing

Assuming you have enough clothes etc., wait until you have a full load before washing. Even on ‘Quick Wash’, two washes will still outweigh the cost of one.

Hang to dry

Tumble Dryers are notorious for eating up your electricity so hang to dry whenever possible. With ‘Retro’ products now in tune, buy an ‘old fashioned’ Ceiling Airer. Heat rises, so even in the winter, with the heating on, this will speed things up.

Detergants

The recommended amounts to use are usually more than you need. Use half the amount and monitor the difference - if any !

Eco Balls

No detergant atall ! Eco-Balls will last up to 1,000 washes before nedding to be refilled. This works out approximately one third the cost of normal detergants

Eco Dryer Balls

No Softeners atall ! These are everlasting. Just put them in the Dryer and the reaction not only does the trick of a Softener, but reduces drying time as well !