I don't know if you can phrase it like this. If there was such an answer to your question you'd know that before you'd know how to write a single line of C. There are many fragmented things each with its own quickly diminishing returns and constituting nowhere near a significant portion of the whole.

Other than that, just experimenting with a project that starts out simple, following through with where it leads you not giving up and seeing how deep the rabbit hole goes has been instrumental in my experience.