Start by identifying the major shapes that comprise the image. These are the shapes that need to be separated from each other for the pictorial space to be apparent.
This market scene depicts a shallow space, crowded with shapes. It is important to make clear where the individual components are, relative to each other. I would want it to be obvious that the car is closer than the umbrellas, which, in turn, are closer than the sunlit people. Beyond them are more people, subsumed by the deep shade. For each of the major shapes in your scene, draw a simple outline to locate it on the picture plane. Remember, this is meant to be over-simplified. We only need to know where the shapes are, not what they are.
Next, block in each of the shapes with a first layer. The layers will progress from light to dark, allowing each successive layer to be applied on top of the previous ones. To help see a couple of layers ahead of yourself, try asking, "Is there a way I can paint the entire shape with a wash that will underlie everything that will come later?"
There is another progression that parallels the movement from light to dark. Thinking of the information that is being depicted as starting out very general and becoming more specific, layer by layer, is a good way to keep from putting in more than the viewer needs to be shown. In the deepest shade in the market scene, for example, it is difficult to know exactly what those dim shapes are. Instead of leaning in very close to the picture to try to make them out, lean back, and let them be vague. Give the viewers an opportunity to interpret part of the scene for themselves.
Some parts of the picture will be sufficiently depicted after two layers. others will need three, or maybe four. If you feel the need to use more than 4 layers, it's time to rethink your approach. This is meant to be too simple. It is not a painting, it's a tool for learning how much information is enough. Just because you can see it, doesn't mean it belongs in the picture.
Use three colors, one red, one blue and one yellow, to make all the colors you see.