For the screen use the black cloth that came with the macbook.
If you don't have it you can use the leather "smammie" style towels sold
at Wal*Mart. Chamois cloth. http://www.touchoforanges.com/bluchamclotp.html
By the way, the original Mac one, the black one, is machine washable for those who didn't know.
If you have neither, use windex and a paper towel. Amonia free or whatever.
I glued a cotton ball to the head of a battery powered fan that had lost its blades to the cat. I generally find you can make the case look as good as new if you slightly dampen the cotton bud, then buff the machine one panel at a time.