Watch this video created by the University of South Australia Library. It was developed to address the most common citation mistakes law students make as identified by Academics from the UniSA law school.
The citation style adopted by the UniSA Law School is the Australian Guide to Legal Citation (AGLC) third edition. AGLC is published by the Melbourne University Law Review Association and is available to download free from the University of Melbourne by clicking on the link above. You can't print the guide, but you can save a copy for your personal use. Printed copies of the AGLC are available for loan from the Library.
If you are unsure when to refer to your sources or how to use footnotes, you will find assistance and examples in the extremely useful book by Anita Stuhmcke, Legal Referencing (4th ed 2012, LexisNexis guides). Chapters Three and Four in particular contain a wealth of advice on 'Legal Referencing' and 'The Fundamentals of Legal Referencing and Writing'.
To help you understand legal citation, check out the workshop Academic Referencing Tool (AGLC3) - produced by La Trobe University produced by La Trobe University or the Overview of the AGLC 3rd Edition produced by the University of Southern Queensland.