First, select a battery profile that will use less energy.
Menu => Settings => Battery Manager
Then, Turn off the automatic applications sync.
Menu => Settings => Data Manager => Data Delivery
Next, Turn off the Bluetooth power
Menu => Settings => Wireless & Networks => Bluetooth
Finally, turn off the Wi-Fi
Menu => Settings => Wireless & Networks => Wi-Fi
That's it! Your battery will now last longer. However, if you do not want to give up these features, but you still need more battery life, you might consider purchasing an extra battery or atleast an extended battery.
