Charge it every night and unplug it in the morning. Nothing special.
+1
Also, do the following:
Turn off Wi-Fi during the day (when not connected of course)
Turn off Bluetooth during the day (if you have no devices or car)
Turn off Background App Refresh for non-essential apps
Turn off Location Services for non-essential apps
Turn off any Maps or GPS running behind other apps
Turn off Stocks or unnecessary apps in Control Center
Turn off Motion on wallpapers
Shut down any Games running behind other apps
Turn down the Brightness to 30%
Turn Auto Lock to 1 minute
Those are the main drains on battery life that most people don't realize. Can't tell you how many people leave wi-fi and Bluetooth on 24/7 who don't own a car and don't use wi-fi. Can't tell you how many times my daughter runs three versions of the Sims and leaves them running in the background on my wife's iPhone.
Myself, I put wi-fi on in the house in the morning and evening only. I leave Bluetooth on all the time for my car. I do the rest of what I recommend above. At the end of the day I have 25% battery life when I hit the pillow and plug back into the lightning cable for my daily overnight charge.
BJ