In this post, I summarize my learning problems to advance from an intermediate R level. I suggest finding projects you are interested in and inspecting their codebase at GitHub. In a certain sense, you could use the skills of those experienced persons who guide the project/repository for mentoring your own learning advancement via GitHub. Maybe there is even a possibility of getting involved in the project and learning from relevant real-world challenges. — My example is with R and GitHub, but the learning strategy I recommend here should be usable for other programming languages and other collaborative version control systems.