how would you revise for history?Watch this thread
If you struggle remembering factual details then perhaps create acronyms or associate events with places in your house/ a journey (I think this is called the memory trail method).
Another helpful thing to do is to try and teach somebody else a topic/ event etc as this will solidify your knowledge + make you aware of things you are not certain of.
Make sure you understand the mark scheme as well + read the assessors report.
Hope this is helpful