Hey, I saw this link in the GADS 2020 Slack channels.
There was something I expected you to mention - Documentation.
I have found that learning how to read Docs is the single best way to hone your development skills.
It can be long and daunting to read, but it's ALWAYS worth it. After all, all those who make tutorials first read the documentation well enough to understand it. Then they experiment with the options to understand it further.
It's also good practice to keep a cheat sheet close at hand.
Further, I would say that it is good to make notes whenever you learn any new tech.
Cheers.