Here is a quick exercise that I think is good for progressing a loose style in our painting. Here I worked on an A5 sheet of cheap watercolor paper, 1 medium mop brush, and 3 artists quality tubes of paint - ultramarine blue, cadmium yellow and cadmium or alizarin red.
I did this in about 10 minutes while sitting in a coffee shop. My local friends will know it must be Costa opposite the station lol.
A simple pencil sketch no detail, brush in a first layer of yellow/red to stand for the lighted areas, place the figures and traffic, paint in the shadows in a few bold minimal strokes mixing all 3 colors. Get darks by adding very little water if any.