When deciding on the type of visualization to use for a specific dataset or audience, I consider a few key factors. First, I assess the nature of the data and the story I want to convey. For instance, if I'm dealing with time-series data, a line chart might be appropriate to show trends over time. If I need to compare categories, bar charts or pie charts can be effective. I also take into account the audience's familiarity with data visualizations. For a technical audience, more complex visualizations like scatter plots or heat maps might be suitable, whereas for a non-technical audience, simpler visuals like bar charts or infographics might be more effective. Additionally, I ensure that the visualization aligns with the key insights or messages that need to be communicated, keeping it clear and straightforward to avoid any misinterpretation.