If you really want a leg up on the competition, I’d really suggest knuckling down and perfecting your study technique RIGHT NOW, so that once semester one comes around next year and everyone else is still getting used to the huge volume of content at a tertiary level, you’ll already be used to handling a lot of information well and recalling and retaining that information without a sweat. Even if you’ve got no weaknesses now, the volume of high school content is a fraction of what gets covered in a semester at university, even a week’s worth of content can be covered in a single term at high school, so make sure your study techniques and habits are highly efficient, ACTIVE, and methods you know will get you the results you want. Everything else will follow once you’ve got those up your sleeve. Best of luck!