I clean mine two to three times a year, I've done it on all my cars and my wife's as well. I use a generous amount of Simple Green from a pump spray bottle, a soft paint brush for stubborn spots and a stiffer brush for really stubborn spots (like around the power steering cap and bracket) and a gentle spray from a hose to wash the grime/dirt/grease away, top and bottom. I will dry what I can with a towel or rag then drive the car until the engine bay warms up enough to dry the remaining water. Sometimes I will "condition" the plastic and rubbery parts with a protectant like Armorall. Be sure to cover your power steering reservoir cap with a plastic bag to prevent water from entering thru the small weep hole before spraying anything! You may need a few paper towels to soak up the water that will accumulate in the wells on top of the struts, too.
