How to Clean an iPad Screen

The critical point to remember is 
.. Never use a cleaner or solvents
.. Only use water and a micro-fiber cloth

For all those that prefer a step by step procedure:
1. Unplug your iPad.
2. If you keep your iPad in a protective case, carefully remove the case.
3. Lightly dampen the cloth with water. Do not use cleaners or solvents. Make sure the cloth is free of lint.
4. Use the cloth to wipe the screen. Start at the top and use gentle, side-to-side movements to clean the entire screen. Do not get moisture in any openings, including the camera or the headphone jack.
5. Allow the iPad to air dry.
6. Replace the protective case.

Also, see 'Clean Your iPhone'