To be a security guard in Australia you must be an Australian or NZ citizen or have a Visa that permits unlimited work rights and obtain a security license.
To get a security licence in Sydney you must first complete a CPP20218-Certificate II Security Operations, pre-qualifications including being 18 years old, a fit and proper person to hold the class of licence, no criminal record.
The best course for a security guard is to obtain a security licence, CPP20218 Certificate II in Security Operations. Study with Multisec Training Auburn.
Security Licensing Enforcement Directorate is empowered to administer the NSW Security Industry, including all security training.