Use colour...colour solves everything.
Try and make notes (eg. spider diagrams) all on one page per topic?
For example, for biology, you could do colour coded cell diagrams, and have the page full of information only about cells?
Diagrams always help, as they ensure you actually know the stuff you'll be talking about ^-^
In history (idk if you even do it) but timelines are so helpful.
Maths, practice papers...many many practice papers. Actually this is key for all subjects... maybe try doing one 6-marker for each subject each weekend? Including marking it, so you know the information AND what the exam-board wants? :3