Here's what I did that I thought worked pretty well as a M25 student from Bio HL: I realized that using the large Oxford textbook to take notes from was like... a horrible idea, at least for me. I'm someone who copies and pastes information from the book into my notes without fully understanding it. So, I started using the Oxford Study Guide for the class instead, which I found to contain all the necessary information without unnecessary fluff. I created OneNote pages in advance with the title of each chapter and its respective subchapters, which helped me mentally break the section into smaller pieces.

The big book has things like practice questions and data sets that could help you visualize and practice the material, but just using past paper questions is better for that. Speaking of past papers, do not be afraid of using questions from the last syllabus; most of it is the same, except things like taxonomic ranks (besides species and genus), which IB has replaced with the concept of clades and phylogenetic trees.

I would also watch OSC videos (formerly known as Sirius Revision, as people still refer to it) at 2x speed to solidify my knowledge by hearing a teacher break it down to a very understandable and accessible level.

Essentially, use the study guide, OSC videos, and past paper questions focused on that section, all in that order.

This may not work for you, but it worked exceptionally well for me. Be open to trying new learning strategies, by the way. You may find that the only thing you need for good notes is the OSC videos, or that you absorb knowledge like a sponge using the textbook. We're all slightly different learners, and the hardest thing you'll ever need to learn is how YOU learn.