My method is always isopropyanl alcohol (can't spell, just search iso alcohol in Amazon) and pour a generous amount of the screen and the back and wipe until it dries up which it does within seconds.
I am not trolling you but it does work, the highest alcohol volume it is and it is registered as electronic safe. If it is somehow contaminated too badly or can't get iso, I get fairy liquid (washing liquid) and a flannel in hot rinsed water (not scolding to your hands) until it is damp and not dripping and wipe all over then dry it with a towel.