Really depends on the person. Know the concepts, examples, practicals well. Since it's a note based sub, a lot is memorising. You obviously do this by summarising notes (each syllabus dot point) in your own words by how
you understand it. For each dot point write down things you know about that topic. Summarise this further, drawing the main points. This tends to help with memory easily. Add in diagrams or whatever you need to for parts that you may find difficult or not quite comprehend from the content. You can use acronyms for remembering things like different stages in meiosis. Once you know the content well, you need to apply the content effectively (this is where many people lose marks). Past papers + grabbing bio textbooks with questions having worked answers will help as you're forced to learn to apply the content, and see where you needed to improve to pick up those extra few marks. Not only that but you get used to the type of questions they're gonna ask you and you'll know what to expect so you can ace it. Discussing as a group will help to ensure you actually understand the material, with a lot of content, active learning helps. Also for bio specifically, keep in mind that knowing glossary key words is legit key, knowing 'assess', 'evaluate', etc. Not that hard of a subject, good luck to you and the rest of the 2018ers.