I got an A* in GCSE for AQA but this was back in 2013, I mainly just read the revision guide and instead of trying to answer the question myself I just read a question and turned over to the answer. I found in GCSE most of the questions were the same, so once I noticed those keywords I'd just write what I memorised in the revision guide.
There wasn't really much to it, so it was easy to memorise as most answers were a couple of lines long at most.
OIL RIG
EDIT: Yes to the guy who linked that textbook, it is literally all you need.