Change your light bulbs to LEDs. 

Automate lights and fixtures using timers or smart devices.

Use natural light whenever possible. 

Seal cracks, gaps, or leaks you find and add insulation, if needed.

Change your air filters regularly.  

Turn off the lights when you're not in a room. 

Reduce cooling and heating times when possible. Or use a smart thermostat.

Unplug any electronic devices that aren't
being used. Unplug your cell phone
once it's charged.

Wash only full loads of dishes and laundry.