You need to make sure that you regularly close all applications.
It helps to turn Auto Brightness off and manually set your screen brightness. From the notification bar at the top of the screen uncheck the Auto check box and move the brightness to about half way.
Next, turn location off on the notification bar. Next, go into Setting > Power Saving and turn on Power saving mode. I don't use Ultra power saving; it seems to waist more power.
Next go into Setting > Bluetooth and take the check mark out of the checkbox to make your device visible to other devices. If you need to "pair" another Bluetooth device put the check mark back, pair the device, then take the checkmark out again.
Don't complain about battery life if you are tethering your phone. Good technology, but battery life hog.
Next go into Setting > Wi-Fi and uncheck the Smart network switch. This is a battery hog and will continue to switch between networks especially if your Wireless Wi-Fi at home signal is low. So, when you go to bed at night the signal might be switching between Wi-Fi and 4G.
Did I mention Settings, Location and turn it off until you need it. Then turn it on, use it, then turn it off when done.
Turn of Settings, Connect and Share, Nearby devices, NFC, and Screen Mirroring.
I love air view under Setting, Motion. Very cool and does not use much energy.
So when all is said and done.
Screen is at 45%
Cell Standby at 16%
Wi-Fi at 11%
Device idle 10%
Android system at 6%
Android OS at 5%
and then I have two applications that I need to have running at 4% and 2%
That's it. My Battery life is great. Oh, and did I mention that you should get into the habit of checking and closing the apps that are open? Simply press the application button, bottom left of your phone. swipe the application to the left and the application will close.
Make sure that any application that you install does not use notification. What does this do? it constantly checks the internet for updates and it will push you notifications. This especially true for apps that are on a game board of some sort.
Your mileage will very, but following these simple steps will increase your battery life. I have full battery charge every morning.
Good luck :-)