1] When you get a new phone, it is advisable that for the first two to three cycles, let the battery completely drain out (till the phone switches off) and then recharge.
This ensures that your phone battery is able to function at full capacity. Also, do this once every month to ensure optimum battery performance.
2] You can easily save on battery and system memory being used by regularly checking the task manager. Close applications that you are not using.
3] Bluetooth is a major battery hog. Keep your Bluetooth switched off if you don't need it to save battery.
4] You can also turn down the brightness of the screen to get better battery backup.
5] Animated themes, operator logo and screensavers make your phone look funky, but they drain the battery too.
6] Additional services such as GPRS and WiFi should also be shut down as soon as your work is through.
7] When at home and office, keep the phone in silent. Ringtones use both the speaker and the vibrator function which leads to more battery consumption.
8] Try to avoid using the voice dialing feature if you want better battery life (especially in a phone with large 'contact' database).
9] Go to Display settings, and reduce the values of power saver time-out and light time-out.
10] Games use almost all the functions of the phone from the screen, speakers, key press to vibrator. Minimize playing games on the phone if you need your battery.
11] Clean your battery's metal contacts every couple of months with a cloth moistened with rubbing alcohol. This keeps the transfer of power from your battery more efficient
12] Always use an original charger for your handset. Using fake chargers could damage the battery or the device.
13] Leaving your battery to charge overnight won't damage it. But no longer than that. The average phone battery charges in 2-3 hours, try to keep the phone charging for that specified time only.
14] USB charging and car charging takes longer than the wall charger and also doesn't fully charge the phone. So always prefer to use a wall charger.
15] If you do not care about WCDMA, then in tools/settings/network ¬switch from DUAL to GSM (applicable in selected phones).