Turn off radio communications that you aren’t using. If you aren’t using Wi-Fi, Bluetooth, or GPS, use the Settings menu to turn them off (Note that the GPS receiver is only turned on when you’re using an application that makes use of it).
Turn down screen brightness and set a shorter screen timeout.
Turn off automatic syncing for Gmail, Calendar, Contacts, and other applications if you don’t need it.
Use the Power saver mode switch in the Settings menu.
Use the Power Control widget to control data activity, Bluetooth connection, GPS connection, syncing activity, and screen brightness.
Use the Quick settings in the Notifications Panel to control sound, Bluetooth power, NFC power, GPS connection, and airplane mode.