As a recently finished yr11 what I can tell you is consistency will be key. Yes you could spend the nights before your exam cramming but it may affect you on the day. The main revision advice I'd give is little and often, do past paper questions, but don't berate yourself if you don't finish an entire past paper in a night it's okay, as long as you know what you're doing and earn those marks you've accomplished your goal for the day. Personally it depends on how you learn and what GCSE subjects you've taken but the biggest helpers for me were GIZMO, and Seneca, for my humanities and sciences, for English doing practice essays with ChatGPT assistance, and for maths I did past paper walkthroughs, if you do MFL utilising the resources your school has given you and practicing your speaking and writing will be in your best interest.
Secondly, your point about the mark-scheme not aligning with your points is something I sympathise with and honestly it's going to happen to the best of all students, my advice for this is just answering past paper questions and finding similarities within the mark-schemes over the years, getting advice from your specialist subject teachers is always a good idea too. Mark-schemes change and are finnicky so it may best you sometimes, and that's just something you'll have to accept even though it's absolute insanity.
Finally, you'll never be 100% prepared for all the questions when you open that paper, the best thing you can do is walk in with a fuelled body, well-rested mind and a calm demeanour, don't let yourself crash and burn (like I did in my English lit exam 😅) take every exam as it comes, go day by day, stressing out over an exam that's passed is inevitable but don't let it cloud you, it'll be the worst mistake you make during your exam. I also cannot stress this enough but, TAKE ADVANTAGE of all the free periods you have, every free period I used as a study session and revised the hell out of the subjects I wanted to excel at, you'll thank yourself I promise you.
(Also this may be a bad tip from me and others are free to disagree, but if you're going to a less competitive college/sixth form and they only ask for certain grades for certain subjects, having consistent grades overall will look great, but don't stress yourself if you have a weaker subject and you don't need it to get in. For example one of my friends struggled with Geography, she revised and did the bare minimum in the exam knowing she'd get at least a pass, she didn't let the possibility of failure get to her because she knows she doesn't need it to get into her sixth form. Basically if you don't need it, don't stress it. That's just my personal view tbh)