Stop complaining that the iPhone battery does not last even a day when you have all the functions on the phone kept active. Your music is on, auto lock is disabled, Wi-Fi is on, mail checking option is on, voicemail is on, brightness of the iPhone is set at the maximum, bluetooth is on, etc. How do you expect the battery to last very long? The simple trick to make the battery last longer is to use features only when you require them.

1. Cycle iPhone once a month: Once a month charge your iPhone to 100% and let it run down to 0% percent charge and shutoff. This cycles the lithium battery inside the iPhone. This ensures correct display of your charge status.
2. Use limited mail account: Turn of the auto check option for e-mail ids that you don’t use often. This will not only save the battery but also your iPhone CPU. Go to Settings > Mail, Contacts, Calendars and set the e-mail accounts that you don’t use frequently. This reduce the time for your iPhone to update and and cycle within the mails that you receive on the enabled mail accounts.
3. Use auto lock: Set the auto lock at Never and see the effect it has on the battery. This setting really eats away the battery. Set the option at the minimum of 1 minute or 2 minute. Go to Settings>General>Auto Lock and Select 1 minute or 2. Even if you set it at Never, use the Power button to put your device off  when it is not in use. The first option works better.
4. Turn off bluetooth when not in use: If you are not using a bluetooth device such as a headset, toggle the option off  in Settings>General>Bluetooth off. That saves battery.
5. Turn Wi-Fi off: When you are not using Wi-Fi, learn to put the option off in Settings>Wi-Fi Off.