These tips come from Southern Electric.  They are arranged according to the costs saved:-

1. An energy-efficient fridge/freezer – saving £38 a year
2. Insulating your hot water tank – saving £35 a year
3. Installing inexpensive seals on doors, windows and letterbox – saving £25 a year
4. Setting the water thermostat to 60C – saving £17 a year
5. Insulating visible pipes in the house – saving £10 a year