Start your revisions early and be consistent. Learn the relevant chapters, makes notes, and highlight what's important when they are being taught. This will make the revisions much easier.
Revise in groups whenever possible to make sure that you're covering everything that's in the syllabus.
Do all the homework assigned and practice as many past papers as you can within the time limit as far as possible and check the marking schemes and examiners' reports.
Help others, work in groups and ask for help when you're struggling with something.
Find a proper balance between your studies and the things you enjoy, rest properly, sleep well, eat well and above all don't overexert yourself.
Understand the concepts, try to cover the maximum number of questions in the books and practice as many past papers as possible.
Remember the formats of the statements, don't neglect the theory part, and practice a lot of past papers.
Understand the concept, write the main points (a few words or short sentences) of all the chapters in a notebook and memorise only the essential. You should be able to develop the main points into well-structured answers. Also, read continuously.
Enhance your general knowledge, try to write an essay every week, read the marking schemes, practice at least one section of paper 2 every week.
Know your topics, research essential points for each of them and practice essay questions.