Get can of WD40, spray it on the entire engine bay, you dont need to use all of it just enough to cover it and get in the gaps where dirt/grease collects.
Cover up any electrical parts that could be harmed & the intake.
Let it sit of 5 minutes or so.
Mist spray water over it to run all the WD40 off, it will go milky. I do that for a couple of minutes.
Wipe it all down with some rags to clean and dry it.
Results are to die for, then get some silicone spray or what ever to make it look even cleaner, but don't go OTT so it gets caked in it.
I've done that on all 7 cars Ive owned and it works and looks great every time.
Example on my Legend I cleaned the other day.
Dirty-ish
Cleaned with WD40, water and wiped down (with out silicone spray)