I try to maintain a theme of three colors: red, black or chrome. I guess if you really like the
zinc color under the car, you'll become a fanatic like me. First you wash the top of the car with nothing but hot water and a sponge. Then you wash under the fenders with a hose and a brush and spray everything you can't reach. Next, you dry the top of the car. Then, you move it to a dry spot, jack it up, and wipe everything under it with old towels. I look for loose bolts and nuts and check all the suspension parts while I'm under there.
I hope this helps,
Paul