Stephanie Evergreen (Evergreen Data) and Ann K. Emery have put together this handy checklist of best practice in creating strong, visually engaging graphs for data visualisation. It was specifically compiled with evaluation practitioners in mind and covers a range of areas such as the text, arrangement and colours in a graph.
"We compiled a set of best practices based on extensive research, tested against the practical day-to-day realities of evaluation practice and the pragmatic needs of our stakeholders. ... You, evaluator, will find clear guidelines on how to make the best use of a graph’s text, color, arrangement, and overall design. We also included a data visualization anatomy chart on the last page of the checklist to illustrate key concepts and point out terminology."