Information displays should be annotated, combining words, images, graphics, whatever it takes to describe and explain something. Annotation calls out and explains information and, at the same time, explains to viewers how to read data displays. Good annotation is like a knowledgeable expert/teacher at the viewer's side pointing and saying, "Now see how this works with that, how this might explain that..."
Yehudi Menuhin, a great violinist, marked up a score for Bach's Sonata No. 2 for Solo Violin. Penciled annotations show real-time performance strategies. To outsiders, insider markups appear chaotic and cryptic, but these personal annotations are for Menuhin's eyes, the only eyes that matter. All can learn from this useful workaday grid strategy: a relevant and intense data layer can become a coherent substrate scaffold upon which to overlay additional information. Maps do this all day long.
The Meander (aka Menderes) is a river in Turkey. As you might expect, it winds all over the place. But it doesn't do this out of frivolity. The path it has discovered is the most economical route to the sea.
The river's algorithm is simple. At each step, flow down. For the essayist this translates to: flow interesting. Of all the places to go next, choose the most interesting. One can't have quite as little foresight as a river. I always know generally what I want to write about. But not the specific conclusions I want to reach; from paragraph to paragraph I let the ideas take their course.