Plan your meals and buy only what you need to make them. If a meal features rice and you buy a big bag, make sure you plan rice dishes in future meals iyswim.
Switch off unnecessary lights.
Dry your hair naturally- to see how much this saves, plug the hairdryer in near the meter, switch it on and watch the meter spin round....
Aldi and Lidl really are cheaper, the food's good and they do do things like free range eggs.
Unless you live in the middle of the nowhere, walk more than drive. Remember when you used to walk or cycle for miles as a teenager to see friends, well....
Invest in a sewing machine if you don't have one, make do and mend, transform old stuff like trousers into skirts etc (some investment in a book on how to dress make may be required).
If you are a gym member, drop it and run outdoors (lethal ice permitting).
Make your own spray detergent with 1 part white vinegar, 2 parts water and a splosh of washing up liquid. It lasts ages and can be used on most surfaces.