There is a bit of a hint in the photos
I used enamel paints as they stick better to the hose. Paint goes on, using either a paint brush or toothbrush. I let it sit for a few minutes and then useing paper towel dab it off, leaving behind a thin film of paint. I then repeat this process with various earth colours over and over slowly building up the grime look till I’m happy.
The couplings use to be shinny aluminium when I started.
Hope that helps a bit.