10A* at GCSE (including 9s in the Englishs) hopefully I can be of use!
Literature
Too many people think literature will be fine if they can remember quotes based off flash cards. Don't fall into this! In your exam, you won't have flash cards with you, so you need to be able to recall quotes at the mention of a character or a theme. Don't get me wrong, flash cards are GREAT, but make sure you get to a level where you can just reel off quotes.
Essay plans are so important! Look at the question style and make a list of every possible question you can think of (I know you can't predict an extract, but you can predict the themes or characters they may ask about) and plan an essay of the key points you would make. For example, with Jekyll and Hyde, write essay plans for the themes of: repression, class, duality, science etc.
Read! Your! Texts! I'd say around 70% of my school never actually sat down and read the text. I'm not talking about analysing it in class, or when your teacher reads it to you. Just sit down and read the damn book and it will make infintely more sense, and quotes will definitely start to stick out at you.
Look at mark schemes, what do the examiners want to see from you? Look at how marks are awarded so you can tick these boxes in an exam.
Do past papers! Lots of them. Ask your teacher to mark them and get some critical feedback. DONT be like me and just do the past paper questions that look the easiest.
Resources I love: Eve Bennett on Youtube for motivation and general English advice and an amazing essay writing video, Mr Bruff for specific revision on texts and exam technique, I also read several essays by university scholars about Macbeth in order to get some good arguments. I didn't find revision guides much use.
English Language (the bane of my life)
Oh boy, I hated English Language. We barely covered it in lesson and to be honest, I didn't know what it was until mocks. If I can get from a 5 to a 9 in three months, so can anyone!
Past papers are completely the only way to get better. Unfortunately, there are very few out there. I managed to hunt down about one past paper from AQA and one that I found online by a school. I got my teacher to mark it, and then criticize it, then I would redo it until I got a mark I was happy with. I could then use that paper with a good mark as a template for future ones! When I ran out of past paper resources, I simply chose a book at random, picked out a random extract, and made up a question similar to those I saw on past papers. It doesn't matter that it's not a perfect past paper since it is still revision.
Mr Bruff definitely helped, he has a series on English Language and how to respond to each question. This is so useful! Make sure that when you are in an exam, you know EXACTLY what each question wants you to focus on. Different questions want you to comment on different literary devices, structure, and so on.
For creative writing, it's very tough. I would recommend analysing some really good descriptive writers (I highly recommend Margaret Atwood for this). I also read poetry (e.g Sylvia Plath) since poems are dense in literary devices and beautiful vocabulary you can roll off. I had a full poem by Sylvia Plath basically memorised, and I used some extensive vocabulary that I knew from that poem, nothing wrong with taking inspiration! Also, punctuation, paragraphs and coherent writing are so important. One English teacher told me to write each piece of punctuation (;:-,.?!) at the top of the page and tick them off as I used them to make sure I had a variety. I would also recommend reading some news articles right before the exam, they're great as a source of inspiration for creative writing, and they really help you get in the frame of mind to write something like a letter or a newspaper article in Paper 2.
Resources: I used the Eng Lang revision guide by Mr Bruff, and a YouTuber that really helped my Eng Lang was English with Mr Salles. To be honest, most my Eng Lang resources were simply my teacher and practice!
Maths
Maths was my biggest struggle at GCSE, it took me ages to stop getting 5s and 6s and get up to an 8 on results day. Maths is one of those subjects that you can't cram - things like Maths, Languages and Eng Lang are skills that progress with time. Don't leave it until too late to start revising!
Past papers with maths are absolutely essential. It's all well and good being able to do the content, but can you apply it to a question?
Revision guides are so useful for maths. I used the standard CGP AQA Maths and Further Maths guides (for maths and further maths respectively) and they were so good! It meant that I could cover absolutely everything. My general way of revising was by doing past papers, and if I was stuck on a question or got it wrong, I would reapproach the question using the revision guide so that I would understand. Then I would do all the questions that were in the revision guide on that topic to secure my knowledge.
Also, don't just learn the quadratic formula and sine rule, make sure you can spot where you need to use it!
Resources: Various Youtubers, if I didnt understand anything, I would just search it and there was always plenty of maths revision. If you need questions on a specific topic, just google 'circle theorem questions'. Also the CGP AQA 9-1 Maths guide was so useful! Many of my friends used CGP workbooks and they seemed helpful, however I don't think they are too accurate in mimicking actual exam questions.