Although I'm a very disorganised boi, I have some tips.
1. Make as much room for study every day as possible - personally, I quit cocurriculars and sports that I wasn't passionate about, gaming with friends, etc. To make more time for study. Think about it, the time you invest in your future is basically your job as a student. You're taking 2024 HSC so take yr10 as an opportunity to play hard before you force yourself to give up some of those other things that aren't studying.
2. Study as early as possible - doing homework straight after school or during free periods in school, waking up early and working before school instead of that 1 am night grind helps a lot as your concentration levels are much higher. Avoid studying beyond 10 pm if you can.
3. Study for 50-70 mins at a time, and chunk all your to-do tasks each day into those (you can put more than one study task in one chunk) so you can reach the 'focus zone' that takes like 23 mins to achieve (which is why Pomodoro is not as effective as it might seem). I use a watch or you can use the new 'focus' clock feature in WIN11 to help me do a 50min sesh and 10min break where I stand up, stretch, get food/water, do pushups etc
Every 2-4 hours take a longer break (30-60min) to eat meals and do other stuff.