Unplug any cables, and turn the iPad/iPhone off by pressing and holding the Sleep/Wake button until the red slider appears.
Grab a soft, lint-free, slightly damp cloth. Try not to get any moisture in openings on the iPad/IPhone.
Avoid using household cleaners, window cleaners, alcohol, aerosol sprays, solvents, abrasives, or ammonia to clean the iPad/iPhone.
The iPad/iPhone screen is coated with an olephobic coating, to remove screen smudges from the oil left by your hands, simply wipe the iPad screen with a soft, lint-free cloth.