I also remove the casette and drop it in a bucket with degreaser and water. Then with some latex gloves or dishwashing gloves I scrub each sprocket with a Park Tool cassette brush. Toss each one onto a dry rag to dry.

I bet it sounds like I'm some sort of perfectionist with too much time on my hands, but I actually only do this about once a month, and it usually only takes about 15 minutes. Just gotta have the right tools.