Charge till 100% full, however long it takes. Let it trickle after that for say 30 minutes (means leave it connected to charger after it reaches 100%).
From there use it in one go without charging until almost 0%.
Then charge it in one go without interruption till 100% full. You can let it trickle a little bit.
The above is called calibration.
If you decide to leave your phone turned off and unused for a long period of time, do it when the battery is at 50% capacity.
Always use a genuine wall charger, and a genuine or certified cable.
Heat will damage your battery.
Extreme cold will diminish its capacity temporarily, until the temperature rises again.