1) Make sure your cylinder is adequately lagged at all times
2) Ensure that your radiators are hot throughout
3) Check that your system is regularly inspected.
4) The flame in the boiler should be a clean blue flame
5) check the water pressure on the boiler so that it is between 1 and 2
6) By turning your thermostat down by just 1 degree could save you about £60 per year.
For more tips contact your local plumber.