Edward Tufte describes 6 fundamental principles for analytical design (that he claims are merely mirrors of 6 principles of analytical thinking).
In brief these are;
(1) Show comparisons, contrasts, differences.
(2) Show causality, mechanism, explanation, systematic structure.
(3) Show multivariate data; that is show more than 1 or 2 variables.
(4) Completely integrate words, numbers, images, diagrams.
(5) Thoroughy describe the evidence. Provide a detailed title, indicate the authors and sponsors, document the data sources, show complete measurement scales, point out relevant issues.
(6) Analytical presentations ultimately stand or fall depending on the quality, relevance, and integrity of their content.
Matt