I need HELP!!! Biology ,chemistry and psychology

What are they best ways to revise for these a levels?

For Biology and Chemistry, the key is to understand the content and then learn to apply your knowledge by doing many past paper questions. It's vital that you learn from your mistakes, then make a note of these mistakes in a document and go through it every week to make sure you won't make them again.

Chemrevise.com has great notes for Chemistry and you can use YouTube channels such as 'Eliot Rintoul' to help understand each topic.
For Biology, learning the notes from this page: https://www.thestudentroom.co.uk/showthread.php?t=5062288 and doing as many questions as I could get hold of has greatly helped to improve my grades.

I learned a lot from watching the 2 following videos, where a student explains how she got an A* in both Biology and Chemistry:

Hi there! For Psychology, I found it best to revise the content (and by extension evaluation points) by writing my notes in the structure of possible 12 and 16 mark questions I could get (I did AQA, I don't know if the structure of questions is the same for every exam board?) Then, I'd test my knowledge by writing out the 12/16 mark question or just quiz my knowledge with some short answer questions. This way, I'm ready to tackle any run-of-the-mill basic question pertaining to the topic, and I have a nice structure for the info I can just alter slightly depending on the specifics of the question and/or how many marks it is worth. Not sure if that'll work for everyone, but it helped me condense what I need to know and put it in an exam context all in one.