The "one big idea" is the main idea or focal point of your infographic, which you will then support with data and visuals. It's crucial because infographics are meant to be "snackable" and should ideally focus on a single, clear message. This main idea guides the entire creation process, from data selection to visual storytelling.
This video, the third part of a beginner's guide to creating shareable infographics, outlines the essential steps to take before the design process begins. It covers defining the target audience and goals, choosing the medium, selecting and organizing a topic, finding and processing data, identifying the story within the data, and structuring the infographic's copy.