What do I need to know before this?

A paper, article or course that keeps losing you for reasons you can't identify.

I want to understand the material below but I keep getting lost. Map the prerequisites.

1. List the concepts the material assumes I already have. Include the ones it never names, which are usually the ones that hurt.
2. Arrange them as a dependency order: what must come before what.
3. For each, say how deep I actually need to go. Passing familiarity, working knowledge, or genuine fluency? Most of them will not need fluency.
4. Mark which ones I can safely skip on a first pass, treating them as a black box.
5. Give me the shortest path: the minimum set, in order, that gets me able to read this.

Material or topic:
What I already know:

Planning and retention. Working out the order to learn a subject in, and making it stick once you have.