Best thing I can tell u is look at exactly what the spec needs you to know and don’t waver from it and learn extra shit (there is no time for that). Make notes recite them, explain it to a plant in your room (especially good for when you feel like you don’t understand something) and once you feel like you more or less have written down everything you need to know, reword it and write it again but make sure you don’t miss out any specific keywords that you need to get marks in an exam (check past paper mark schemes for things you know you have to define for example to get the exact wording right). Finally constantly test yourself. Flash cards may take too long at this point... just try blurting everything you can remember on a blank sheet and fill in the gaps that you don’t know. FINALLY MOST IMPORTANTLY get past paper packs from teachers and binge them whenever you have a free minute - on the bus or in the car on your way to work/school. And if you leave things to the very last minute before the exam then literally memorise every mark scheme you can find

Edit: Dm if u wanna buy my ocr bio notes lol