Even with a microfiber cloth and water, be careful when cleaning. Don't just rub hard to get the marks of. If there is any dirt or tiny particles, you can scratch or wear the coating.
The safest method (IMO)
> Wet a microfiber cloth thoroughly, wring out only the excess...it should still be pretty wet
> gently wipe off the screen. This will remove foreign matter that may cause scratches. The water will act as a lubricant to mitigate any scratching.
> follow up with the dry microfiber cloth. Again, gentle pressure but you can use a little more than the previous step