It takes about 4 hours plugged at 10 watts to have the device fully charged. The battery lifespan should cover 1000 full charge and discharge cycles.
1. Always makes sure that it has the latest software.
2. Keep Auto-Brightness mode on.
3. Turn of Wi-Fi and 3G if not available or not in use.
4. Switch to airplane mode in areas with poor or no coverage.
5. Minimize use of location services (Maps).
6. Turn off Push Notifications (App Store, Apple Push Notification Services)
7. Fetch new date in lesser frequencies by switching to Manual Mode.
8. Turn off Push Mail and minimize updating emails real time (Yahoo! or Microsoft Exchange).
9. Set iPad to Autolock in a minute.
10. Use iPad regularly and charge at least 1 cycle per month.