Switch the vibrate function off on your phone, using just the ring tone. The vibrate function uses additional battery power. Keep the ring tone volume as low as possible.
Turn off your phone’s back light when not in use. Turn off your phone’s back light. The back light is what makes the phone easier to read in bright light or outside. However, the light also uses battery power. If you can get by without it, your battery will last longer. If you have to use the back light, many phones will let you set the amount of time to leave the back light on. Shorten that amount of time. Usually, one or two seconds will be sufficient. Some phones have an ambient light sensor, which can turn off the back light in bright conditions and enable it in darker ones.
Avoid using unnecessary features. If you know it will be a while before your phone’s next charge, don’t use the camera or connect to the Internet. Flash photography can drain your battery especially quickly.
Keep calls short. This is obvious, but how many times have you heard someone on their mobile phone say, “I think my battery’s dying,” and then continue their conversation for several minutes? Sometimes, the dying battery is just an excuse to get off the phone (and a good one, at that), but if you really need to conserve the battery, limit your talk time.
Turn off Bluetooth. It will drain your battery very quickly.
8Same goes for WIFI, GPS, and infrared capabilities, if your phone has these features built in. Keep them off except when you need them to save power.
Use GSM rather than 3G – Using your phone in 3G / Dual Mode will drain the battery quicker than if you just use GSM mode – have a look at your phones spec and you’ll see it will quote two different battery life times – normally 50% more for pure GSM use.web browsing use sites like bGoog.com  that display a black Google background instead of white.