I've cleaned my monitor with a bit of spit and toilet roll, probably a bad idea, but it seems OK so far.
Haha well, I'm lazy, so it's either bog roll or my sleeveFor the love of god don't clean your screens with toilet roll, not only will it scratch over time you will just be putting loads of dusty crap on it. Damp cloth, gently wiped the same way, then do the same with a dry cloth. Always make sure their clean too.

) it would depend on whether you live in a hard water area and whether the screen was glossy or matte. You can generally 'get away with' using tap water but if you live in a hard water area residues can be problematic and can even damage glossy screens in particular. I would recommend using a proper cloth and cleaning solution or a little distilled water and IPA if you're a cheapskate. Just to be on the safe side. No spit, vodka or toilet roll please!