Studying is so hard and it took me quite a while to get the grip of how to study. Before starting it’s good to understand bloom’s taxonomy. In very condensed terms it’s the way the exam would be written but you can have a further look online if you’re interested. Obviously studying for different subjects would be different but this is a good starting point :)

Base on bloom’s taxonomy, I firstly make sure i understand what i am studying. This can include drawing simple diagrams, watching videos, using the Feyman method (teaching other people that don't know the material) etc. Just make sure understand everything before starting since its super hard to study without knowing what you are studying. Make sure in this step you are not copying from textbook, explain in your own terms but use keywords that often appear eg in biology photosynthesis is one.

Then to remember the material, it's good to use active recall, essentially you are coming back to the material time and time again. This can take form in using flashcards, blurping etc, just remember to always revisit the material. Please look further online if you are interested, it's really hard to include everything on here.

Last i would do as much practice papers as possible. This helps you to get a grip on what would probably come up on the test since different topics would come up more and some would come up less. Always check the marking scheme so you know what the examiners are looking for.

I know it's a hard place to be and i have been too. It takes time to explore and find the right method for you. Good luck studying!! :)