When art delivers more than ambiance, emotion, or lyric, it's probably illustration. Conveying information through art requires visual organization, prioritization of what's essential, and aesthetics that welcome.
Visual organization can be chronological—for procedures or stories, spatial for maps, categorical, semantic, or symmetrical—whatever fits the project at hand.
Once a framework is determined, the artist needs to stay on task. Unless the project is a Medieval manuscript, function should preempt decoration.
That said, presentation must catch a viewer's eye and keep it happy to the end. For that, a well-planned color scheme, compositional balance, and meaningful visual variety are essential.