I'd add two things that Sveta didn't mention:
1. Turn off Cortana's "hey Cortana" voice search. It's always sitting there in the background wasting power, and if you are anything like me, you rarely speak to your PC. Type Cortana in the search bar and hit "Enter." Switch "Let Cortana respond to Hey Cortana" to off.
2. This is super simple, but it saves the greatest amount of power in one fell swoop: turn down your screen brightness. It may take a few minutes to adjust to a dimmer screen if you've had brightness maxed out, but you will quickly get used to it. As an added bonus, it can also be easier on your eyes.