Some great suggestions here already but thought I would add Metacademy [0] and L...

Some great suggestions here already but thought I would add Metacademy [0] and Learn Anything [1] (White Paper here [2]). These are designed to create a map of skills and concepts for a given topic. I find an interactive visualisation to be really effective in understanding the broader ideas before starting out or during the early stages when it’s hard to see how the pieces fit together.