hey, i'll address these one by one

chemistry -
when i first tried the 'using your knowledge questions' in nat5, i would try to write a coherent paragraph, which would usually result in me rambling and mentioning irrelevant things. The advice i got from my teacher was to use bullet points or, in some cases, diagrams to explain things. I found that helped. For me, it was the formatting of those questions that threw me off, and that's the same formatting i used in higher and am using in advanced higher.
If you're struggling i'd say to try wrap your head around the content you're learning, ask your teacher to explain it again, or go onto bbc bitesize, mrs adams on youtube or even see if your school has any 'how to pass' or 'bright red' textbooks they could let you borrow or you could find them at a low price second hand. Understanding the content i find is major since most questions want you to use the theory to answer questions rather than memorize exact answers if that makes sense. I can not stress enough how much past papers matter, and if you get something wrong try to understand where you went wrong, and if you still don't get it try to find a time your teacher can explain it to you. Your teachers want you to get a good grade and do your best so even if you feel like you're pestering them (i did feel like that a lot) just remember that they'd prefer you sought out help than quietly struggle.
Higher chemistry builds a lot on nat 5 chemistry and i found was quite a big jump in terms of content and the level of content. Before making this decision, i'd try to narrow down what you want to do at university if that's the path you're planning on going down and see what subjects they want, for example, i'm applying for pharmacy, and for that chemistry is a must have, but if that's not the case for the course(s) you are going to apply to and you don't have the motivation for higher i'd maybe consider taking another subject. Your teacher likely has an idea of whether you could do higher chemistry or not so for a more in-depth discussion i'd go to them again.
Modern studies-
i used the pee structure for my answers. I did flashcards on quizlet for the topics, for example, 'social causes of crime' i'd then have the sub-topics like drugs, peer pressure... And a statistic for them. You can check out mr marr on youtube as he goes over how to answer these questions and do past papers. My teacher told me about what i think is called 'man on the street knowledge' where you could make a hypothetical example instead of an actual one as long as it is relevant (e.g for poverty and crime. For example an individual below the poverty line may resort to crimes such as shoplifting and theft to provide necessities due to not being able to afford them) but before you do this i'd just double check with your teacher as i am not up to date with the current marking instructions. If you forget mid-exam try to logically think about it, because in my nat 5 prelim that happened to me but for questions like powers of the police, effect of crime on victims... You can think like 'what do the police do? Right, they patrol, they deter crime, okay what does that mean, it means they patrol to deter crime as their presence may make potential offenders rethink their actions and also they can catch crime taking place if it does occur, for example, the police may patrol shopping centers to prevent and deter crimes like shop lifting' i did that in my prelim and got full marks on a question and i did end up doing this two times on the exam and still got an a1. Again, please check this with your teacher.
English-
for ruae, i read through it once and underline any key points, and key keywords i see so that when i read the questions i have an inkling of where things are and have them highlighted. My strategy was to first answer the questions i had an answer for so that they were out of the way and then try the ones i didn't understand as much. I found that sometimes when answering questions i would think that 'this is too simple to be answered' but sometimes that is the case. I made flashcards for the different tones and what they meant, and different writing techniques such as minor sentences, repetition, lists, and so on.
For my set text poems i revised key quotes from the poems. Obviously, if you can memorize all your poems that is great but i revised quotes that i could fit into multiple questions and that i could analyse quite a bit. I also re-read my poems a lot so they were in my memory but not at the forefront so if needed i could try to remember the poem vaguely. Connotations and word choice are your best friends, if you're ever struggling to analyze something go for a word and its connotations and then explain how it links to the question.
For my textual analysis, i did prose. I memorized a max 2-3 sentence summary for the text to put in my introduction to save time. I did not memorise the whole text but a general summary and quotes. I knew where the quotes fell in the story such as 'in the beginning, in the middle, in the end, and what events were happening at this time' and i revised the analysis for these quotes that my teacher gave.
I hope this helps, if you need me to clarify anything feel free to ask
