DataWrapper is an excellent tool for making attractive charts, made by a team that includes a lot of journalists. It’s essentially free until you are a very heavy user. They also have an excellent blog with lots of good design tips.
Flourish (owned by Google) is another tool for making charts which also has a pretty generous free use plan.
This is not a book. It is a one-of-a-kind immersive learning experience through which you can become—or teach others to be—a powerful data storyteller.
(Requires a free O’Reilly Learning account; see the front page)
A tool for choosing colors for data viz, with accessibility accommodations built-in
ColorBrewer: Color Advice for Maps
The classic, research-based tool for selecting color schemes for map-based viz. Jankier interface though.
The Functional Art: An Introduction to Information Graphics and Visualization
Website/blog associated with a series of excellent books by Alberto Cairo, who also makes the Data Journalism Podcast. See the Alberto Cairo page on O’Reilly Learning for links to full book text, video courses, and an Audio Book.
storytelling with data
Website associated with a series of excellent books by Cole Nussbaumer Knaflic; it also has a blog, a podcast, videos, and more. The full text of Storytelling with Data is available free through O’Reilly Learning, as is “Let’s Practice” (see the Make section above).
Data vis do's & don'ts - Datawrapper Blog
The Datawrapper blog has lots of great info, but especially this category is full of design guidelines that are useful whether or not you are using Datawrapper to make your charts.