By diming the screen of your smartphone, you will notice an instant change in battery life. This option is usually found in the Settings menu. If there is an Auto-Brightness option — use it! This will give you the optimal level for usage.
Your battery is constantly being drained when your phone is searching signals for Wi-Fi, 3G/4G or Bluetooth. Esp. when there is little-to-no reception, you will see a significant drop in battery life from frequent signal searching.
This one is simple. If you are no longer using an app — close it. This will prevent your phone from running multiple open apps, slowing down your productivity and killing your battery. The battery will also drain faster if you are using several apps at once, for example — surfing the web while listening to music.
Other than closing out apps, the location services should be your next go to. This will slow down the efficiency of your phone since signals and data continue to send and receive when left running in the background.
This is by far the best kept secrets for saving battery life. Similar to Wi-Fi or Bluetooth, your phone burns up the battery searching for signals. Use this when you are in areas that can’t reach a signal. If you are able to find a power source and need a quick charge — use this and you’ll have a fast, longer-lasting charge.
How to extend your iPhone or Android's battery life by The Guardian: http://ow.ly/CcvPJ
How to squeeze the most juice out of your phone battery by Digital Trends: http://ow.ly/CcwYz
22 Tips to Extend iPhone Battery Life by About Technology: http://ow.ly/Ccx67