I've never done it on any of my previous cars, mainly because I'm afraid of causing something to break.

What do you clean, and what do you use? Diagrams/photos would be a bonus

 

I just use a dilluted solution of simple green in a spraybottle and lots of
paper towels to degrease and clean. then mist with water and wipe all
of it off.

this year, i will use Nero to dressup the plastics.

 

Lazy Way-
I also use diluted Simple Green in a spray bottle. But then, while it's still wet, I spray everything down with WD-40. Don't laugh, it works! Requires hardly any work at all and looks great for quite a while. I only do it once every couple of years, depending on how much the vehicle is driven.

 

^^ then all the bolts and nuts start fallin' off.

imagine the mist of WD40 on the waxed panels...oooo.... bad bad bad!

 

http://www.autopia-carcare.com/inf-engine.html

Use a soft brush. I have a separate boars hair brush I use just for engine cleaning.