What are some genuinely effective ways you’ve cut down your energy bills?

We had a new boiler installed last year. A Combi. Did away with the cold-water tank in the attic and an insulated hot-water tank in the spare-room cupboard. Increased insulation in the attic. Some windows got new double glazing. OK, that was major, relatively expensive work. We also drained the central heating system and removed all the built-up sludge. We air the rooms most days for a few minutes every day to reduce the risk of mould and damp. We have installed thicker curtains in the living room, where we spend most of the time. We only have the heating on when we need to, depending on our work patterns. If we're both out at work all day, the heating is off until shortly before we come home. We have a smart thermostat that we can control from outside the home, so we can make adjustments if needed. We cook mostly on a gas hob, and only use the oven a couple of times a week. We often cook enough for two meals at once, then reheat the leftovers in the microwave the next day. We don't run hot water any more than necessary. We make sure we have a machine load of laundry before we do it. We have a heat pump tumble dryer, but we also use the washing line in the back garden when time and weather allow. We also air-dry some items on a clothes horse in the garage, so they don't contribute to damp inside the house. The main computer stays on 24/7, but the monitors are switched off. Since our new system upgrades, our energy bill (electric and gas) has gone down by £65 a month.