It can sometimes be difficult to find a strong underlying abstraction to construct your drawing upon. The image of the jungle below is one such case, there are no obvious large divisions of space such as land and sky. In this case it is best to describe the light and shadow areas. The identification of these areas will differ from person to person. So what you are looking for is what’s known as a ‘notan’, an abstract image of just black and white blocks. It’s perfectly acceptable to use artistic licence when designing the underlying abstraction because it needs to be interesting, appealing and balanced.
Identifying the medium blocks is also challenging but there are a few shapes that stand out. These are areas of strong contrast between the lighter value leaves and the darker value shadows.
Looking for shadow shapes is always helpful in drawing especially when it comes to portraits.