So I was actually in quite a remarkably similar situation to you. I do basically the same subjects as you (3U Maths, Physics, Chemistry, Engineering Studies, Business Studies, and Advanced English). I was in the top of most of my classes throughout year 10 (excluding english) and I'm maintaining/improving that in the preliminary course. I have a few pieces of advice for you.
Routine and Study Habits
Work on a routine. What do you do when you get home from school? What do you do with the pages of notes and worksheets that you accumulate throughout your school day? What can you do to these to further improve understanding and recall? I created a routine where upon arriving home, I typed up my notes to a OneNote file. This acted as a sort of revision for me (albeit not very effective), then I would file the notes away until a week later, where I would process them once more doing various activities with them to further improve retention and understanding. Make sure you have a method worked out so you can apply this to your future years, and keep working on this method to improve it. Think about how you're going to study, as this can be so much more important than what you're going to study.
Mindset and Motivation
Make sure you are ready to go hard or go home. Maintaining, or even more so, improving your position requires a lot of effort. Year 11 and 12 is where a lot of people start taking things seriously, which means you will have a lot more competition. I always say that if you want to do well, that's fine, and if you don't want to do well (you want to relax, take it easy, focus on things other than school) then that is also perfectly fine. I believe both options are acceptable, and you should choose just how much you want to do in year 11 and 12. Whatever you do, don't choose to do well and fail to deliver on that promise, because that's just lying to yourself.
Create the concept in your mind of making deadlines and sticking to them. Remember that if you achieve a few deadlines in a row, you end up on a streak, and that positively reinforces you to achieve further deadlines, ultimately placing yourself in an upwards spiral. You want to be in an upwards spiral throughout the year and to do this you need to honour every single one of the deadlines. As soon as you break one deadline, you can break out of this upwards spiral. As a sidenote, this also means that the deadlines you set for yourself must be achievable, otherwise you're setting yourself up for failure.
If you have any questions, feel free to ask me.
