The iPad site at Apple shares a few tips that will help you improve the battery life of your Apple iPad. These include:

• Minimize use of location services: Applications that actively use location services, such as Maps, may reduce battery life. To disable location services, go to Settings > General > Location Services or use location services only when needed.
• Turn off push notifications: Some applications from the App Store use the Apple Push Notification service to alert you of new data. Applications that rely extensively on push notifications (such as instant messaging applications) may decrease battery life.
• Adjust brightness: Managing the screen brightness is the best way to extend iPad battery life. You can adjust brightness yourself; go to Settings > Brightness & Wallpaper and drag the slider to the left to lower the default screen brightness.
• Fetch new data less frequently: The more frequently email or other data is fetched, the quicker your battery may drain. To fetch new data manually, from the Home screen choose Settings > Mail, Contacts, Calendars > Fetch New Data and tap Manually. To increase the fetch interval, go to Settings > Mail, Contacts, Calendars > Fetch New Data and tap Hourly.

You can find more tips on extending iPad’s battery life at Apple.com.