A little bit of practice in observation. Simplifying and picking out the shapes and shadows is an exercise that I do not spend nearly enough time doing.
SO here's a couple of entries into my sketchbook with watercolour and ink+watercolour.
I'm hoping to get out and do a little bit of urban sketching in the next week or so and want to brush up a little before then. These aren't quick enough for that but at least are helping me remember the exercise. I look forward to doing more.