This one might be a no-brainer for most Kindle users, but for new users it might be a helpful tip. The easiest way to preserve battery power is to turn off your wireless connection. The switch is on the back of your Kindle, next to the power switch. Whenever you’re not actively using the wireless connection, you should turn the switch off.
You should only turn it on when you’re browsing the Kindle Store or the internet or when you need to download something you purchased on Amazon.com from a computer. Any other time – when reading a novel or managing your content, for example – you’re just wasting your battery power.
UPDATE (3/25/09): This information also applies to Kindle 2, with the exception that the wireless is no longer controlled by a physical switch but through the Menu by choosing Turn Wireless On or Turn Wireless Off.