Hiya!
I've just finished year 12 and I also study Sociology and Politics. In my mocks I got an A* in both.
Politics is quite content heavy, and having examples are quite key to essays. As such, I can't stress enough how important it is to be informed on current affairs and recent history. Particularly, knowledge of the 'Brexit era' will be tremendously helpful to you. Knowledge of PMs, scandals, quotes, political events, statistics or anything of that nature will be useful.
In terms of note-taking and remembering all of the content, flashcards are the way to go for me. I will say though, revision techniques are wildly different person to person. For example, I've never made a flashcard for Economics as I don't see them as the right technique for the subject. My routine for revision involves making digital notes from the textbook so I can literally 'work though' the content, then I make flashcards on my notes.
For sociology, It's the same but I cut out the note-taking. Sociology is full of names to remember, and I find note-taking pointless here. I'd estimate in year 12 there's about 125 ish names to remember, having just looked through and counted my flashcards which amounted to 142.
I will just reiterate what's been said by
@Godisgood1234. It took me till Christmas of year 12 to finally land on revision techniques that worked. I jumped around from physical flashcards and notes to mind maps to settling on digital notes and flashcards after being introduced to the app "Obsidian", linked
here. It's fantastic as it's all open source, so there's plenty of community plugins for flashcards, notes, highlighters and whatnot. I couldn't recommend it more. Also, as has been said already, don't be disheartened if you aren't creating A* level responses at first. Across the year, I've seen remarkably steady progression with my essays with some anomalies. Since April I've plateaued. Initially, I spent a lot of time planning essays and getting the technique right. Then, once I had this down and was content with the marks I was getting from homework's, I began doing them with very little prep, maybe 10 mins at max. As long as I maintained the marks, I was happy as I was doing them in less and less time. Again, as has been said already, doing recaps and revision bit by bit throughout the year is key. I stopped reviewing content around a month before mocks to just solely do past papers under timed conditions, then hand them into teachers. On that note, don't be hesitant to give teachers past papers or questions to look at that you've done. Drop them an email, go see them in person, ask for advice etc. I was stumped with Economics essays early in the year and frankly began to hate the subject for it. The questions might as well have been written in size 0 font as It would have had no bearing on my answer. So after lessons, I requested advice from my teacher, and it was helpful. So in short, just ask teachers if you have any questions or problems.
NB: I do AQA for both subjects.
I do hope this helps!