Becoming a Laureate really is up to luck. Whilst the financial incentive is more than real, I do believe in hindsight that the system focuses way too much on academic excellence, which has over the years been translated almost to rote learning and tailoring answers for the mark scheme/examiner's report. These are proven to work, but in the long-run serve you absolutely no purpose.
Do not thus let yourself be constrained by the syllabus. Explore topics in further depth as you wish. Keep challenging yourself, not just academically, but also as a person. Take part in as many extra-curricular activities as you can. In the end, you will have ample time to cover the syllabus content over the 2 years.
The HSC exams are more like a marathon than an actual frenzied sprint. So, work hard, heck yes! But do also play hard. For it is the memories made along the way with friends and teachers that you will cherish the most.
As old-school as it sounds: Make the best use of your teachers - not just academically, but also about life in general. Each and every one of them will have some tips they can help you with. They once were just like you: regular school children. Further, they have seen and helped many many students mature into the well-rounded adults they are today, so make sure to use their experience of life over and above their experience at producing Laureates *wink wink*.
All the above probably are of no help if you are pursuing this dream of becoming a Laureate. I heard those very tips myself from those before me and brushed them aside for the most part. But in all honesty, they are the most important ones. For, the academic rigour you already have is surely already enough, so just be confident in your abilities, and make sure not to pressure yourself too much. Pressure does break people; it is no myth, sadly. So, keep working hard, and hope for the best.
Ps. some tips which were shared with me over the years will be covered next for your satisfaction.
Practice is key, and so is reading.
1. Read, anything - even subtitles on Netflix.
2. Practice writing essays. For, as tedious as it may be to start with (yes, I also spent 4 hours writing half an essay in Lower 6 and gave up in the end, so GP was huge stress in the end for me). So, dig in. For, writing is all about your personal style and covering as many topics as possible. Both take A LOT of time, but once you have your style nailed down and the necessary breadth of knowledge, odds are you will find the GP paper as easy as it gets. There is no secret formula here.
Make sure to challenge yourself with harder questions. The Ah-Teck/Mungur past papers as well as Eric Lam's book are a good starting point, and will surely help develop your logic and reasoning. And if you really enjoy the challenge of Maths problems like some of my friends, then give the AMC questions a go - not my personal favourite though.
For exams, make sure you understand how mark schemes over the years have wanted students to present answers systematically. And no 'silly' mistakes.
Again, a bit like for Maths. Developing your reasoning and logic is key, and this comes mainly by challenging yourself with harder problems. Also make sure to get a good understanding of concepts first, and never to learn by heart - it will not work. If complex concepts are hard to understand, go back to basics (use youtube videos) and build up from there. As bad as it sounds, make sure you learn your definitions well. Practising papers and marking yourself with the mark scheme will be of most help here. Though effective, it won't serve you any good beyond the exams.
Personally was not my favourite in HSC, as I always found it just learning and memorising stuff, with a tiny bit of logic (for organic). But if you do love Chemistry, make sure to ask questions for it really has much more to it than what we learn in A-level, and is simply quite fascinating, esp. where Chemistry meets Physics. For exams, I think practice as many papers as possible, and try looking for patterns of answers examiners have seemed to be looking for over the years.
Learn systematically. As much as biology is about a lot of memorisation, I always made sure I created my own mnemonics to remember stuff or just looked up some online - trust me, someone out there on Reddit has already come up with one. From there on, make sure to remember that plants as well humans are one whole organism, so make sure to be able to link up the different systems and pathways together.
For exams, practice as many questions as possible, not necessarily writing all of them down, but maybe orally, jotting down your main points, and then checking with your teachers and mark schemes (are really not nearly as exhaustive as required for biology). This and making sure you dissect the MCQ questions (actually a technique that works in Chemistry too - i.e. what your answer would be without looking at the given choices and then figuring. out why each answer is wrong) will help develop clear out tons of misconceptions you naturally build up as you learn stuff.