A lot of hard academic research is going into visualization design. Reading some of the material is a great idea when you're looking for something specific—like how best to transition between a scatterplot and a histogram (http://vis.berkeley.edu/papers/animated_transitions/)—but coming up to speed on such a vast field takes time.
For an exhaustive look at visualization methods, take a look at the periodic table of visualizations developed by the KPI Library. You can find it at http://www.visual-literacy.org/periodic_table/periodic_table.html.
The periodic table uses six categories—Data, Information, Concept, Strategy, Metaphor, and Compound visualization. Hovering over a cell shows an example category.
The table itself is a well-done visualization. It may not be beautiful or artistic, but emulates the common periodic table perfectly. It immediately draws our attention and sticks in our mind because of the familiarity, and presents the data well. On the other hand, there...