How can I clean my LCD monitor?

Okay, I have an Acer P225HQ 21.5” monitor for my PC, and the black case around it seems to be getting pretty dusty now. I cleaned it with LCD screen cleaner (since I had nothing else) and its already dirty again within 12 hours. What do you suggest I buy to clean it? I am not sure what sort of material it is, but it seems to be a shiny black plastic. Hope that helps o-O