Keeping your drive train clean is the key to good performance and long component life. It is also a time consuming pain in the ass. The easiest way to do this is to blast the crap out of your bike with a power washer. This is ill advised.
High pressure can force the water and dirt into places that it may not belong. In the frame, in the bearings, all places that should stay dry. When I'm washing my bike, I like to use a garden hose and kitchen brush. These brushes work great, are pretty cheap, especially if you get them at IKEA like me.
50 cents each
They're good for a many uses on the frame, or a few on the greasy drivetrain. The brissles won't scratch up your paint and are great at loosening dirt and gunk. Once they're black, they are not really removing gunk as much as moving it around, so just toss them in the trash.
The life of a brush
So go get yourselves some cheap brushes and give your bike the cleaning it deserves!