Ask HN: What's your preferred way of learning a new stack?

There's no right/wrong answer this question, since everyone has a way that works best for them. What works best for you?

Do you start from the cover page of a book? Do you pull down a sample project and start tinkering? Do you watch tutorials/take courses aimed at that stack?

I'm sure everyone can profit by borrowing elements off of everyone else's ways.

It doesn't just have to be a a stack. It could be a language, framework, or anything in software engineering, really.