One approach. Remember, telescope people are fanatical about cleaning. There are models of telescopes where having never cleaned the lens is part of a sales listing since any cleaning risks scratches or marks that can reduce sharpness or brightness when your eyes and light are at the far limits. Anyway-

http://www.televue.com/engine/TV3b_page.asp?id=103

Oh, acetone and camera lenses are a big no-no. It will dissolve paints, plastics, all sorts of ulginess. Again, astronomy equipment is often constructed differently than camera optics.