When you have fully charged the battery and disconnected the charger from the device, unplug the charger from the wall outlet.
You do not need to charge your battery so often if you do the following:
Close and disable applications, services, and connections when not in use.
Decrease the brightness of the screen.
Set the device to enter the power saver mode after the minimum period of inactivity, if available in your device.
Disable unnecessary sounds, such as keypad and ringing tones.