Here are pictures I took while the battery and alternator were out. I used a low pressure electric washer. First, all the heavy dirt and oil gunk was washed off. Second, heavy duty degreaser was used. Third, tire foam can spray was used carefully everywhere else. Brushes were used to loosen up dirt and grime. The engine bay picture is three weeks after the work. Replacing the filter housing gasket and replacing the power steering hose clamps has kept the engine bay cleaner.
What does your engine bay look like?