Great question. This is where it becomes difficult and time consuming, because it's akin to, "How do I become like [insert athlete]?" What I mean by that is, none of the knowledge or skill that talented people have was developed overnight. There's unfortunately no easy answer about how people come up with this stuff, except they spent a ton of time on it, over many years.
The information comes from numerous resources, such as game developers, various support articles, news articles, leaked or intentional Microsoft internals discussions, Microsoft blogs and learning material, third party tools that dissect or troubleshoot, other people's tweaks, websites, college, and books--the library has all sorts of books with information that simply doesn't exist elsewhere, not even the internet.
Once someone has beaten on a craft for hundreds or thousands of hours, they become confident and knowledgeable enough to where they can then become the innovators. For example, nowhere else on the internet will you currently find a number of my tweaks, because I'm the one that either found them by literally perusing the registry directly, or plucked them out of the deepest corners of the unknown web, and finished seeing them through with proper testing and research, fleshing them out into a usable set of tweaks.
A skill I've tried to instill in people, is to use Boolean Logic (
link2) in Google searches, because most questions have already been answered here or elsewhere, and becoming a great researcher and using time efficiently is step one in mastering computers. The next step is to follow reputable guides as-is, even if the user disagrees with the author's preferences, because the point of that exercise is to gain hands-on experience, so the student can eventually become the teacher. We troubleshoot computers in layers, and the way to learn computers is exactly the same.
