its true batteries will deteriorate over time.. especially if not looked after. Best way to get the longest life out of your battery is NEVER run them flat. Best keep it above 20% at all times. And do not use fast chargers unless you have too.. and don't leave them at 100% for too long. Even better only charge to 80%.. though that is a pain in the butt
i actually have a nice and slow 0.8a charger that i use overnight so i get a nice and slow charge overnight..
i also go into a lot of apps and RESTRICT their Battery usage as well. You can find it under the App Info of your apps and then under BATTERY you can then RESTRICT apps from running in the background. may help you too.