"Hold Option while double-clicking a window's corner to expand the window to fill the screen." - this is the most important tip for macOS, IMO. I still don't understand what's in their heads that they don't maximise Safari/Preview to the full width by default. I have 32" display and I'm using all my windows maximized, I just don't ever want them side by side or something like that.
I am not sure if I agree with the choice either, but that’s the explanation.