I painted the whole building white, not too carefully either.
Then I applied a very dilute black/dirty brown wash, applying as many coats as I felt necessary, and rubbing any excess off before it got completely dry with a piece of paper kitchen towel. I also picked out the odd brick with the same colour wash. Rubbing most of the paint off means that it accumulates in corners where you can’t get to it with the tissue.
That’s about it really for the white.
Jon