1. Shop smart: Look for notebooks with Intel® Centrino® Duo mobile technology, which delivers exceptional dual-core mobile performance with power efficient technologies like Intel SpeedStep® and Intel® Dynamic Power Coordination, specifically designed for power efficiency.
2. Dim screen/LCD brightness: Choose an environment with adequate lighting—less brightness means you'll drain less power from your battery.
3. Run your applications wisely: To get the most from your laptop, even when multitasking on the go, run resource intensive applications just when actively using them. Then make sure to close the applications you aren’t using.
4. Close unused applications: Programs will still use power while sitting idle.
5. Have the right RAM for your needs: With appropriate RAM, instructions run off memory instead of disk. Less power is needed to refresh the RAM than to spin the hard drive.
6. Clean your battery: Rub the battery's metal contacts with rubbing alcohol every two months. Allow to dry before re-inserting.
7. Remove extra accessories: Unplug items like PC cards, USB and FireWire devices that are not being used.
8. Use built-in power management devices: Enable this feature and set your system to "Battery Optimized" mode or "Max Battery" mode. Put your computer to sleep earlier and turn off the screen backlight sooner.
9. If not using wireless LAN to connect to the Internet, turn it off: Wireless LAN access uses power even when it is not in use. Transmitting and receiving data drains the battery.
10. Defragment your hard drive regularly: The built-in defrag utility included with Windows* will take your file fragments and put them closer together on your hard drive, which will decrease hard drive access times and save battery life. 

Read a further explanation on how a laptop uses battery power and additional battery-saving information.