Noah Iliinsky is one of the best presenters on complex visualization tools and techniques. One of the classic stories Noah tells is how he used visualization tools to decide what bicycle tires to buy. In this presentation he talks about design thinking for effective data visualization. This presentation is worth the 18 minutes of your time.
Make sure to pay attention to the section on “How to Visualize: Appropriate Encodings,” which occurs at about 8:10. In this section, Noah covers the properties and best uses of visual encoding. Yes, a bit geeky, but essential if you are a data scientist.