Click Settings app.
iPhone settings are displayed. Click Bluetooth.
As you can see, Bluetooth is switched on. Slide the toggle to the left to switch Bluetooth off.
Notification settings are displayed. Click the app that you are comfortable switching off notifications for. For example, Messages.
The app's notification settings are displayed. Slide the toggle in front of 'Allow Notifications' to the left to turn off notifications for this app. Similarly, you can turn off notifications for more apps that you do not frequently use.
General settings are displayed. Click Background App Refresh.
Background App Refresh settings are displayed. Either you can slide the toggles to the left to turn off background app refresh for individual apps or you can do it system wide. For maximum battery life benefit, turn it off system wide by sliding the main toggle to the left as shown below.
4. Decrease brightness to as low as you are comfortable working with
Click Display & Brightness.
Display & Brightness settings are displayed. Slide the brightness slider to the left as much as possible for you but keeping it too low can harm your eyes so adjust accordingly. Toggle the Auto-Brightness slider to the left to turn it off.
Privacy settings are displayed. Click Location Services.
Location Services settings are displayed. Either switch off the location services system wide by sliding the toggle in front of Location Services to the left or manually set it for each app to 'Never' or 'While Using'.