Wrap all your electrics in Gladwrap or Alfoil. (i prefer glad wrap as it cant short out). The main things are the coil packs, starter motor and alternator.

Get yourself a good quality degreaser. A cheap one can often discolor any raw aluminum bits or other metals.

Some that i have used and would recommend are Autoglym Engine and machine Cleaner, Autoglym PM3 and Duragloss Ultimate Orange Cleaner

I use the Vikan Brushes to get in and around the engine. It saves scraping your knuckles on things and it helps work the degreaser in.

Once you have sprayed it up and agitated it use a pressure cleaner on a low pressure setting and carefully rinse the grime away.

Repeat if necessary