All blackberry users would agree with me that Blackberry is a smart phone with a very dumb battery. Anyway here are some steps you can take to get the most out of your battery.

 
 

Reduce your BlackBerry back light Brightness and also the back light duration and thick “Automatically Dim Backlight” in Screen Display options.
Avoid having several social networks on one phone: Applications like Facebook, Twitter, whatsapp, facebook chat … etc when running all at the same time can really drain the battery in no time.
Turn off background Sync on facebook application: When this is on, your phone periodically sends and receive data to and from facebook respectively and that can really drain your battery.
Turn off all group notifications.
Switch your phone from 3G to 2G: This method increases the battery life by approximately over 40%.
Finally if your battery is in a really bad state already i.e it lasts for only a few minutes, then Try wrapping the battery up in nylon and freeze it for 24 hours. This worked in my case

 
Note: Do the final step only if your battery life is unpredictable.
If anything is unclear, ask your questions in the comment box bellow
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