Knowing your audience can help decide many aspects of your visualization and advocacy. Once you define your target audiences you can start to drill into their motivations: what do they care about? What do they fear? How can you help them take the actions you want? How can you mobilize your allies to reach them?
With target audiences in mind one can start to make decisions about messaging and framing, format and style, the level of simplicity versus complexity, etc. How can you best reach them? What kind of data literacy do they have? What is the best format to reach them? How you can you apply pressure or incentivize them to take appropriate action?