In this scene, for example, the cloud could have a much softer edge to keep it from seeming too solid.
Here, the busyness of the crowd could be in competition with the details of the cathedral. I'd be inclined to soften everything within the middle value shape in the background to make sure the figures stand out.
Using the image you brought home, one of your own, or one from this post, consider what changes you might make to edges, and give your ideas a try. Be prepared to explain your decisions and the results.