1. Turn off Wi-Fi and BlueTooth
2. Don't play computer games, music or DVD movies
3. Disconnect all external device like PC Card modems, Firewire, USB devices and optical drives.
4. Adjust your screen brightness
5. Tweak Windows Power Options
6. Decrease or mute the Laptop Speaker Volume.
7. Turn off all scheduled tasks.
8. Turn off Auto-save features in Microsoft Office and other applications.
9. If your PC has a built-in wireless card, turn it off or disable it when not in use.
10. Programs that are run from a CD or DVD can be copied to and run from the hard drive, which typically consumes less power than an optical drive.

via labnol