Nothing all that special needed on modern vehicles. Yes, I'd cover the switch for the LED's, but everything else is pretty water tight. If there's an exposed aftermarket air filter either wrap it in plastic, or remove it and plug up the air intake tube. Common sense should lead you to not spray water directly into the alternator. Thry to not get too much water into the hood liner, they fall apart pretty easily when wet.
I spray the engine bay down with water from the hose and work my way around with Adam's new Eco All Purpose Cleaner and several brushes; Wheel, Trim & Lug-nut, and different size bottle brushes. Rinse with water from the hose. I'll blow the engine and engine bay dry with my Master Blaster on the 4hp setting or with my Side Kick; then close the hood, start the vehicle and let the heat from the engine dry the rest. When everything has sufficiently dried I'll look things over, and if needed, I'll clean any areas I've missed with Brake and Parts Cleaner, or Carb Cleaner.
I just took care of the engine/engine bay in my 2013 Chevy Malibu this past Friday with the above directions: