They have special LCD cleaners out there, but I tend to just use water. Don't apply the water directly to the screen, though. Wet a cleaning cloth and be gentle. I like using those cloths that they use to clean the cell phone screens.
Just a very very slightly damp cloth, no cleaning products (especially polish). Buff with a dry cloth afterwards to get rid of marks / patterns. There may well be specialist cleaning products, but personally I've never found a need.
They have special LCD cleaners out there, but I tend to just use water. Don't apply the water directly to the screen, though. Wet a cleaning cloth and be gentle. I like using those cloths that they use to clean the cell phone screens.