i just go to the car wash, and use the engine/tire cleaner and soak down the engine and then go to rinse and it comes out pretty clean....

 

Wal-Mart engine cleaner. Cheap and works. Then I mist the engine compartment w/ Armor ALL. Just stay away from the belts. Never a problem yet in over 4 years.

 

I use the Castrol Super Clean degreaser, I just spray it all in the engine bay, let sit a few minutes, then wash it with a hose. Then I spray it with the air pistol to make sure i get as much of the water out of the electrical connections and such.