If you are at a good Australian university, stay there. Look into semester or summer exchange programs, where you could study here for a few months to get an idea of what it is like.
Also, apply for summer internships with international accounting firms, i-banks and other businesses with offices out here. Applications are generally due fairly early in the fall, so spend your summer researching which banks/ accounting firms have HK intern programs you are interested in and preparing a good resume and supporting materials. If your university has a career services center, try using that as a starting point for your summer job research. Don't leave things until the last minute. Summer internships often lead to higher paying jobs if you perform well. However, internships and higher paying entry level positions are not abundant here, so try to present yourself well.
If you land an internship, the company should take care of all your visa paperwork for you, so not having the right to work here isn't an issue.
Also, most expat positions at banks/ accounting firms do not require Mandarin fluency, but it wouldn't hurt for you to take a year or two of the language in school. While a couple years of Mandarin won't get you a job here, it shows that you are taking an interest in the region and looks nice on a resume.