Comment your no 1 revision techniqueWatch
English Language - making prompt cards with exactly what you need to write for each analysis question. It's been a couple years since I did my English Language GCSE, but I remember having some difficulties meeting the marking criteria, so I would say that using the mark scheme and putting in your own words along with comments to yourself using your teacher's feedback (what do you personally need to focus on?)might be beneficial. Again, do all the practice papers you can.
English Literature - I liked to pick random poems and annotate them within approx 10 minutes without notes, and then go back if I missed anything to get into the swing of analysing unseen poetry (which can seem quite daunting). Also, I highlighted the most important contextual points from my notes and made a Quizlet to test myself on the details. Finally, with the new courses being closed as opposed to open book (at least that's what I've heard), quote learning has become much more important. Although my English Lit GCSE novel exam was open book, I had closed book exams for my A-Level French and German exams. I would pick out the most useful quotes for specific topics (for example, the role of nature in Bonjour Tristesse, which I knew I would probably write about) and write them on Post-it notes which I would around my bedroom. When I came to a Post-it note, I would say the quote out loud, close my eyes and try to recite it from memory before checking to see if I was correct. Also, simply writing them out like lines worked for me (boring ik but it was effective)
Biology/Chemistry/Physics - I liked to use the specification for each science to pick out the main topics for each unit and from that make massive posters (at least A3) with the main topics as headers. I would then fill in as much as I knew from memory and use my notes to fill in any gaps, highlighting the stuff I didn't know. I would then make colourful A4 mind maps with only the stuff I didn't know the first time round to make sure I was more secure with my weaker topics. Flashcards were always a safe bet for me, again, focusing on the stuff I was unfamiliar with.
Spanish - I did French and German but the same techniques could be used for Spanish. With verbs, always look for ways to simplify the rules - are there any common patterns? Could you maybe think of pnemonics for certain groups of verbs? I would again recommend Quizlet for vocab (you could use Memrise but tbh I find it a bit of a faff to enter your own words and there's not as many vocab games as Quizlet). For speaking, I would practice as much as I could in a casual setting to get used to speaking confidently in the target language. When practicing for the actual speaking exam, I would shy away from reading out large swathes of text and use bullet points to plan out what I wanted to say, because revising this way helped me become more spontaneous. Also, don't be afraid to speak out loud to yourself if you don't have someone else to ask you questions- you can't just revise your writing and expect that your skills will automatically transfer accross to your speaking.
I know this is a lot, but hopefully you'll find this helpful!