I have heard it said to bag the distributor and the AMM. I worked at a car detailing place and they never bagged anything, I can not remember us ever having a problem on many makes/models, perhaps a few hard starts.
If still cautious try not to directly spray degreaser or high pressure water on the distributor, amm, ignition module, throttle position switch, (ie anything electronic or working as a switch/contact), general wiring and engine sensors seem to hold up OK.
Some places put dye in the oil to find leaks (perhaps with UV light)
Have fun.
Karl