Simply figure out what to tell and how to tell it

Basically, you only have to solve two things to succeed in powerful and persuasive information design: the what and the how. The what is choosing the right data and information that will make up your story in terms of research, priorities, focus etc. The how is solving the way in which your story and data will be communicated most effectively and powerfully in terms of design, creative visual ideas, style, format etc.