The photo of the tree and the photo of the ruined castle are similar in several ways. In both, the main subject is close to the viewer, dense in places and open in others, with a complex profile. Both comprise too many components to count. The painter's challenge is to interpret the relationship between the shape, which dominates the scene, and the elements that combine to create the shape without having to paint so many leaves or individual stones.
What you see when you squint - a middle value shape on a light ground - is a good place to start. First paint the shape, then suggest the leaves or the stones. When you've made enough marks to tell the viewer that they, together, are what add up to the big shape, you can stop. Or, you can keep making leaves or stones all day, if you want to. Whatever your style, you can start the same way; Shape first, then texture, if necessary.
You could combine all the buildings into a single shape here, or you might choose to have two groups, those to the right of the red sign and those to the left, which would give greater emphasis to the space.
How might you separate the figures in the foreground from those in back?
Go ahead, paint all the individual houses in the background, Or not.