How do you study/prepare

This is definitely asked a lot, but after receiving the breakdown of what you did good/bad where do you go after? Say khan academy, do I do all the lessons or only the ones I struggle on. Same for textbooks, do I read the entire thing or focus on what my weak points are. My flaw is that even though I’m aware if I don’t study I’ll get a bad score, I still won’t because there’s no plan for me to follow.

And advice is helpful, thanks in advance!!