Ask yourself how are you studying?
Are you just using notes and memorising them continuously? Are you not doing past papers (not doing enough)?
If that is the case then you will need to change your ways of study (I'm not saying it's bad, I'm just saying change to something that would seem more reasonable) even if you're doing well. That's when studying smart comes in
Studying smart is about studying all your content in a not so long time frame whilst getting really high marks. In my opinion studying smart comes from the following: 1. How you study your content 2. How you study your weaknesses
Most of your subjects should either require conceptual understanding, rote memorising or mathematical calculations
Conceptual understanding mainly comes into the sciences (and maths I guess) and to actually conceptually understand something you should explain it to someone without looking at notes. Conceptual weaknesses should also be studied via watching videos and/or having super detailed explanations with a diagram. To understand something you would need to understand why.
Rote memorisation occurs in English, sciences and the humanities. One of the most effective methods with rote memorisation I've been told is that there is a "finite" amount of content the NESA can ask in your HSC. Also there is also a "Worksheet method" in which you make worksheets (but cut out a few words), print it out then fill it in a few times a day everyday
To succeed in mathematical calculations, practice and perfection is the crux of succeeding in maths. If there are certain aspects in maths you struggle with you should learn from your mistakes by asking for help and repracticing those mistakes from time to time
Of course one of the most important things is "memory retention". This can be done by applying the knowledge you learn on the day e.g. if your teacher taught you word war 1 in modern history, I'd recommend making notes right after and then doing necessary exam questions. If you struggled with something conceptual on the day you were taught it (e.g. newton's laws) my recommendation is watching videos and looking at how science is applied to the real world
Hope that helps
Good luck