I got 9s in all three at GCSE and for history the best thing for me was a combination of retrieval practice and timelines. There is a lot of content so it’s definitely best to start learning it as early as possible. For retrieval practice you can try setting yourself a 5/10 minute timer and write down everything you can remember about a topic, and then look back over your notes and use them to fill in the gaps. You can also use flash cards/ friends and family to test you about certain topics. Once you feel you know the content well enough try planning out some exam questions on a range of topics. This will help you get used to what you’ll have to do quickly in the exam as well as helping you go over the content.
For english language I did AQA so I’m not sure if the questions are very different on other exam boards, but for the questions about language analysis try getting short extracts from both fiction and non-fiction texts and annotating them as much as you can. The more you practice this the more confident you will be in the exam. In terms of the exam itself, read the questions before you read the extract as then you will already know what to look for while you read. For the creative writing section it’s a good idea to have some broad storylines as well as some good descriptive sentences that you can apply to almost any prompt. Some of the best revision you can do for those questions is simply reading fiction, as that will help you get a good idea of the techniques real authors use. For the non-fiction writing try to read a wide range of newspapers and articles, as well as watching a lot of speeches and noticing what makes them successful. I found that question the hardest to practice for, so I think exposing yourself to the various things you could end up writing and then having a go at some questions themselves is probably the best thing you can do.
I realise this is quite a lot of information but I hope at least some of it is helpful!