Go to detailing world forum and blow your load in cleanliness, I'm very finick, but I don't have enough time to do a job that I would like to do, my usually habits are a rinse then snow foam with some ph neutral foam, two bucket method and some quick detailer as I usually haven't got the time to polish and wax properly.

I like the poor boys stuff, use a few AG products and meguires just because the latter is easy to get hold of, I had a dirty petrol filler cap on my s4 and it bugged the hell out of me until it got done, I also hate that dirty crud build up you get at the edges of the lights, thankfully a blast from the pressure washer is good at getting it out most the time.

With engines I've found neat surfex HD or a cheaper alternative is the Screwfix heavy duty degreaser liberally sprayed everywhere, agitate if possible heavy soiled areas and leave for 5 minutes to soak and then wash off with a garden house attachments on a light spray then check main parts are free from moistures like plugs and alternator, I prefer to do it on a luke warm engine as it helps the degreaser and helps the drying off.