Use a soft cloth or rag and wipe it (only for little splotches and finger prints). Using those wont scratch or damage it. If its bad like a liquid or dirt or something, use a little windex spray or something (not to much) and a paper towel or rag to clean it. That should work :)
You get a very damp rag ( with barely any water on it) and then you just rub it gently N the screen. It takes off all the fingerprints, smudges, and any other type of dirt. I hope this is helpful!! :) good luck!!!!!!!! :)
use ammonia free glass cleaner on a cloth (preferably microfiber), but regular windex shouldn't hurt it just don't spray directly onto screen spray onto cloth first. You can also buy wipes specially made to clean touch screens.