THREE IMPORTANT STEP TO MAKE YOUR BATTERY LAST LONGER

While many of us now use mobile phones instead of land-line phones in our homes, these mobile phones come with Lithium Batteries which require some maintenance as long as they are used.
                                  

Turn the phone off. This will probably be the most effective and simple way of conserving your battery’s power. Why? This will help conserve energy and also charge your phone. If you don't plan on answering the phone while you're sleeping or after business hours, just turn it off. Do the same if you are in an area with no reception (such as a subway or remote area, since constantly searching for service depletes the battery fairly quickly.) Some phones have an automatic power save feature, but it takes about 30 minutes with no service to kick in. By then, much battery power has been used. If you don't need to receive or make calls but are using a smartphone as a PDA, disable the phone functionality (flight mode).

2  .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.

                            

3.Stop searching for a signal. When you are in an area with poor or no signal, your phone will constantly look for a better connection, and will use up all your power doing so. This is easily understood if you have ever forgotten to turn off your phone on a flight. The best way to ensure longer battery life is to make sure you have a great signal where you use your phone. If you don't have a perfect signal, get a cell phone repeater which will amplify the signal to provide near perfect reception anywhere.

 I hope this three step can help you,but if you have one you can add it through the comment box...