My device isn't rooted and this is what I do to get the most out of the battery...
1. I try to never allow the battery to get hot in order to prolong its excellent performance. If you're charging your phone, don't run heavy draining apps as this will greatly increase the battery's temperature. When charging my phone, I usually set stamina mode to always on and if I'm not expecting important phone calls I sometimes activate airplane mode. If you want to make and receive calls just turn off Bluetooth, wife, data and GPS while the phone is plugged in to keep the battery temperature down.
2. I used to love the Juice Defender app which was able to automatically turn off Wife/Data whenever the screen is off but sadly it hasn't been updated in so many years. Now I just manually turn off WiFi and Data whenever the phone is not in use.
3. If you're watching an offline film or reading a book, turn off your WiFi and Data. Again, if you're not looking to make calls activate Airplane Mode as this tends to lessen the battery drain especially when watching 4k movies.
4. Delete any apps that you don't use. Especially the power hungry apps!
5. I only tend to set brightness to the lowest setting when I'm in a very dark room. There's no point in always having it so low in broad daylight like a disorientated cave-dweller.
6. When you go to bed, activate stamina mode (if you want to save more juice then also activate Airplane Mode) and just make sure that it won't affect your alarm in the morning.
That's pretty much it for me I guess. Rooting voids the warranty and that's not something I want to do so I'm happy with my current usage and performance.
Hope this helps!
By the way, root seems to improve a lot the phone, but I have Amazon warranty and would be a shame to lose it for rooting the phone