Legal; For all your topics for Legal make sure you have prepared summary notes from the very start of the year as it will benefit you in the long run and make studying alot easier come time for your HSC. Regulary update all case studies and legislation relevant to your topics. Practise essays out of past papers and show your teacher for marking as their feedback will help you achieve higher marks If their is a concept or definition that you cannot understand make sure to revise it until you get a brief understanding that way you will gain better knowledge. For each topic/option list all relevant case studies, media reports and legislation summaries to help you prepare.
Maths; Revise all formulas even though they are provided for you in exams. Understand all the components as part of each formula. Write summaries for each topic with included examples to help you understand the concepts. with anything your struggling on seek help ASAP. Post study notes in places where you always are eg toilet, bedroom , loungeroom that way they sink into your brain without even noticing it as they are always there to look at.