@hollie I guess everyone's terminal journey is slightly different. For me, it was lots of practice. And reading: operating system manuals, books, and (later on) resources on the web. Also, lots of practice. 😊
I have yet to read them, but macOS Terminal and Shell and Take Control of the Mac Command Line with Terminal look similar to the books I learned from back in the day.
Julia Evans' zines are lovely! Once you get the basics of the terminal down, Bite Size Command Line! and Bite Size Bash! might be interesting reads.