I was invited to give a brief talk to the urology department at Northwestern University on data visualization. Recently, you see, many of the residents presented posters at large conferences. When it was time to create posters and graphs, many of them begun to ask: “does this look OK? What can I do to make it clearer?” This presentation discusses some practical approaches to creating data visualizations. The emphasis is on medical applications, but the provided examples can easily work in other circumstances.