Don't use any kind of detergent
Nip down the chemists and see if they'll order you a bottle of isopropyl alcohol. It's very inflammeable so no smoking, but works wonders and if you get it on the label, just let it dry / evaporate. DON'T get it near any acetate!!!!! It'll melt it!
Most importantly is the cleaning cloth; try to get some lint free stuff like base ('uck knows how you spell it), the stuff they use on snooker tables, you can get bits form optitions, but it's bloody expensive from them.