When preparing for Mathematics examinations, the most important thing you can do is to practice! The best resources are past papers. You are encouraged to complete as many past HSC papers from your Solution Books in the lead up to the HSC examinations. These solutions books have HSC exams which have been adjusted for the new content since the syllabus changed. You can also ask your teacher for Smarter Maths worksheets on a particular topic.
Complete each past paper under timed conditions, mark it, then go back and revise any content you found challenging. Do this as many times as you possibly can! Write out post it notes and flash cards on the more difficult topics and use these when revising.
Also, ensure you know the reference sheet well. You need to know exactly what each variable in each formula stands for and where to find it quickly on the reference sheet.
Lastly, ensure your calculator is in the correct mode for the problem you are working on. For a calculus question, use radians unless otherwise prompted.
Best wishes for all of your examinations from the Mathematics Department!