Dont make it harder for yourself

Turn off any electrical devices that are not needed. The use of electrical components makes the engine have to work harder to produce the current required by the alternator.

Obviously, dont drive around in the rain with your wipers off or in the dark with your lights off because it slows your engine down. Just try to avoid using things like heater/blower, radio, headlights, A/C, rear window de-mister while accelerating or driving at speed.

Also keep your windows up. Having your windows down increases the drag produced by your car as it travels resulting in slower acceleration and worse fuel economy. If you have a roof rack that you dont regularly use, take it off. This, like having your windows down produces drag and lots of it at high speeds.