Why, what, how: plan what to learn before you start
Before you learn anything substantial, answer three questions in order: why, what, and how.
Why
Write down the concrete situations you're learning for, each with a rough date and how costly getting it wrong would be. A why that is instrumental (for a job, a decision, a project) tells you exactly what to prioritise. One that is intrinsic (curiosity) tells you to follow your interest.
What
Split the field into what you need: concepts to understand, facts to remember, and procedures to be able to do. Take the list from a source outside your head, such as a syllabus, so it includes things you've never heard of.
How
Look at how others learn it (courses, curricula, practitioners), then decide what to emphasise and what to skip, given your whys.
This order comes from the "metalearning" principle in Young, S. H. (2019). Ultralearning. Harper Business..