How to ensure that you get 10A*s?

Hello,
the answer to your question depends on which subjects you are taking, I did my GCSEs 4 years ago however my advice would be start studying from day 1, I'm not too sure how much they changed them but as far as i remember there wasn't too much content to cover for them so i would learn all the content and understand it fully first, then exam papers, exam papers and exam papers.
If you put in the effort 10 A*s are attainable,
also a general bit of advice is there is no point in studying topics you are good at over and over, find your weaknesses and work on them. Do every paper you can find and bug your teachers to give you feedback.
If you tell me your subjects i might be able to help a bit better, I studied French, Eng lit/lang, maths, science, additional science, further science, geography, history, art, citizenship studies, media studies and IT

How do i ensure that i learn and take in everything properly by January for Maths and May for all the other subjects? What is the most effective way of note-taking and revising?

Maths- learn the theory behind it, usually there is a way to approach each topic and apply it to the question and practice
Science- for bio you need to be able to be good at applying your knowledge, so papers are key! Chemistry is understanding whats going on and not always memorising.
Eng lit is i think analysing a lot but also analysing the key information and not doing it for the sake of it and there were these guides you can get for specific novels or plays and pretty much see how they approach the question. There was a lot of PEEA in my time- does that still exist?
French- vocab cards, learn most common words and basics, audio podcasts- try not to use google translate as much XD- i would know lol
Hope that helped, again i have said this already but papers are key to success and also examiner reports.

I started of secondary with targets of C's and D's and finished year 11 with gcse grades: 4A*s and 6As. Here is my advice, pay attention in lessons take down notes and if you dont understand something always ask the teachers, stay behind if you have to, do all your homework because, it acts as revision without you noticing. When revising for maths use videos and websites and that goes for any other subject because, you might come across someone who explains things better than your teachers. Do A LOT of past papers because the same questions could come up in your actual exam but they might be worded differently. Make flash cards on each topic of a subject and try memorise them then get someone else to test you (I think this help the most along with doing past papers) you can colour code things and in the exam see a topic that comes up remember the colour and you will know what you wrote in that colour. For maths also practice and practice and practice!! Honestly just keep going over everything daily in small portions instead of doing your revision last minuite because you will remeber less if you cram everything in day before the exam and you can be less stressed. I know a lot of people who found memorising through spider diagrams really easy so you could give that a go for any subject.

If you have coursework work super hard on it and take all the help you can get because it can really boost up your grade, I know so many people who dropped two grades because their coursework was bad.

You could try and figure out how you memorise things better so what type of memory you have, visual? Make diagrams, draw things, read and colour code. Listening? Watch videos and actually reading helps too. If you rememebr things through doing? Then do past papers and write things out.

Hope this helped and good luck

Got 8 A*s and 2As.
For essay-heavy subjects like English Lang+Lit and RE, which I did, I found doing exam papers over and over again really helped. I would email essays almost daily to my English teacher and get him to mark them so I could find out what improvements I need to make. Also for RE mindmaps are really helpful and flashcards to memorise quotes, which are useful as references when making points in your responses. Brainscape is an app I downloaded which saved my life! You make notes on there or questions and your own responses to these, your own free online flashcards!
For science in core I got an A but got this to an A* in additional. Balance between reading the revision guide and doing papers helps. I would time myself, read a page in five minutes and summarise each page from memory before turning the notes into flashcards on brainscape which I revised from at the end of the session or on my way to school. Also CGP app is really helpful as this made it easier for me to remember formulae for chemistry, equations, key facts and the like.
For Maths I got an A* and honestly best advice is to go through exam papers while revising. Like for questions you don't understand, flip through your revision guide, teach yourself the techniques needed to answer said question, do some mini-questions on the topic using the book or an app like pixlmaths, and then have a go at the question again. Flashcards can help to keep equations and graph types on your mind. Also on YouTube there are videos where teachers will go through past papers to show you the best techniques. Just type in ' GCSE Maths [insert exam board name] past papers' and these will work miracles - they did for me!
Sorry if this is wordy haha Best of luck !

Pro tips 'ere

Don't worry about it being too wordy, every word of it showed the value of your wisdom so thank you so much for writing all that, it really helped