But before you sell your iPad, be sure to do a
Restore from iTunes on your computer. This will make sure that all of your personal data and settings (like for your email and iTunes/AppStore account/WiFi password,etc.) and erased.
To backup your iPad, open iTunes on your computer and you can either sync or right-click on your iPad and select
Backup
Once you do this, you can
Restore your iPad. When you do, you will get this message --
After you go through this process and your iPad comes back in iTunes, you will get this message. You will want to set it up as a new iPad.
Once you do that, you will get this message --
You can check the options to sync the songs and applications so it will be all ready for the new owner!