Break the chain w/ this (make sure to use the proper drive pin for Shimano or Campy chain - 8sp, 9sp etc):
Soak the chain in Simple Green or whatever enviro friendly stuff you prefer (if it ain't green I will call you an American
) and then scrub cassette, sprockets and chain with this:
Always replace pin on broken chain with a quick link or product specific replacement pin. The quick link will make things easier for the next service. Example of "quick link" sometimes refered to as "master link":
The master link will make it possible to "break" your chain w/o replacement pins or even a chain tool.