1. Turn off Background Application Refresh – Settings -> General -> Turn off Background App Refresh.

2. Switch off Automatic Downloads and Updates – Settings – iTunes and App Store – turn off automatic downloads.

3. Switch off AirDrop – open the Control Center and swipe it up to switch off AirPlay.

4. Set alerts to None – Go to Settings – Notification Center and set alerts to note.

5. Brightness – keep as low as possible

6. Turn off Frequent Locations – Go to Settings – Privacy – Location Services – System Services, and toggle of the Frequent Locations.

7. Switch off Email Push

8. Turn off Bluetooth and WiFi when out of range

9. Switch off Location Services

10. Controlling WiFi and Bluetooth settings

11. Restricting Cellular Data -When you don’t need mobile data for apps and services, turn it to off.

12. Reducing Motion -In the Settings menu, go to General, Accessibility, Reduce Motion.

13. Cutting down use of dynamic moving wallpapers

14. Managing Siri -With Siri being enabled, your iPhone will be constantly monitoring movement. This uses more battery so go to Settings,General and then to Siri.

15. Turn off Spotlight search. Settings, General, Spotlight Search.

16. Turn off iTunes Sharing, Mobile completely, Music EQ and restrict add tracking.

Do you have any other tips to add to this?