If you're anal like fishbonez and Veloc, then you can go the hardcore of cleaning like how Fishbonez put it.
If you're an ass like me, this is what I do :
Leave car to completely cool (no heat at all) --> High pressure rinse--> soak in off-the-shelf engine degreaser--> scrub everything with RM5 Daiso brush--> high pressure rinse--> drip dry / blow dry everything. Start engine.
No need wrap anything or whatever la.. just don't go and jam the pressure hose right into anything specific and electric. Getting it wet won't kill it, getting pressure hosed for more than 10 seconds in one area will.
But that's me la.
I bear no responsbility for any damages.