This is my personal approach. I usually start the engine and have it rolling. I use water to wet the engine, followed by purple magic, and then high pressure onto the engine. I am usually careful around the electronics/electrical and air intake.
I don't bother with oil afterwards, you can use WD40 (water displacement) but that's a personal choice. Personally any oil is going to attract dirt.
Pay attention to where is the dirt before you wash it. Dirt means it has stuck to accumulated oil that leaked spilled from somewhere. Just saying.