Edward Tufte is the godfather of data presentation/visualization. He seeks a more unified, holistic, and integrated model which makes learning more accurate, intuitive, simple, and fun. His books are beautiful and "self-exemplifying" - meaning he wanted the books themselves to reflect the principles he wanted to get across.
I have been studying Tufte’s work with a specific project in mind (to be revealed soon), but his key tenets are important and applicable for anybody seeking to better understand how to use data and visualizations to most effectively teach others, make effective presentations, and, inversely, to understand why certain images and techniques are ineffective.