For essay subjects, essay plans are your best friend. i did mine with headers for intro, para 1, para 2 etc and had bullet points with key quotes or information I would include in this paragraph. Take essay feedback seriously and if you are unsure why you lost marks, ask your teacher to go through it with you, then you can critique it yourself and maybe rewrite some parts of the essay so you have a great template for what you could write if that Q comes up on the exam. i used quizlet for any quotes, critical analyses or statistics I needed to remember for my essay subject (english lit) and I had the app on my phone so i could just flick through it if I was waiting for the bus or walking home from school ect.
Markschemes and Specifications are key as they have all the condensed info word for word how the examiner wants it. When you feel you have revised all the content thoroughly, go through the spec with a fine tooth comb and tick what you do know and highlight what you feel you could cover again. Practice papers are great but dont use them too early as you may be limited in resources by the time you get to your exam. in bio examiners love to recycle Qs so if you have a good grasp of the style of Qs and markscheme answers then you should be good
Lastly, you dont have to work for ages every day, i would just keep up with notes and hw in frees and revise thoroughly for even small tests, take feedback seriously and refresh on your notes every so often and you will be fine! Good luck with your subjects 😀
Context: Im a 2nd year a level student and I live in NI so we still have AS levels which I got AAAA in chem, bio, maths and english lit in August. pm me if you want to talk more, im happy to help 😀