When deciding on the type of visualization to use, I first consider the purpose of the visualization and what insights we want to convey. I then analyze the data type, whether it's categorical, numerical, or time-series, and assess the volume of data to ensure the visualization remains clear and effective. For example, if I need to show trends over time, a line chart might be appropriate. For comparing categories, a bar chart could be more effective. I also take into account the audience's familiarity with different types of visualizations to ensure the information is accessible and easily understood.