I do the following and have had plenty of positive results.
1. spray a little water on the engine, 2. Mist amazing roll-off on the engine.
3 any tough grease spots get treated with Gunk engine degreaser. It's a citrus engine spray but any solid APC will work!
4. Let the roll-off sit for a few minutes.
5. I agitate the engine with a daytona speed brush with a bucket of grease cutting dish soap (dawn or Ajax), rinsing the brush every so often in the bucket.
6. Spray with water to remove all soaps.
7. Blow any crevices and wipe surfaces with a towel.
8. 303 Aerospace has worked GREAT for me on trim and engine covers. I never knew what to use until someone recommended 303 and now I haven't switched. I use it on my own car and it does last!
Engine detailing can be scary because you don't want to get water in the wrong spot and have the car not start. The less water you use, the better! I've been adding engine bay detailing more and more now as an extra. It's a great touch and most people don't even think to clean under the hood so when you show a clean, dressed engine, you look like a star!
Happy Detailing!
