Subjects like Business Studies, Legal Studies, General Maths, Senior Science, etc are basically designed for people who are doing the HSC from a perspective of interest, rather than in the context of further study.
That said, if your desired career path is through TAFE, then these subjects are ideal for developing your interest and giving you a better basic understanding of these fields. If, however, you want a Uni degree, I strongly advise you to take the more difficult, abstract subjects (eg general maths --> 2 unit, business --> economics). They are admittedly more difficult, but also give you a much better grasps of concepts built upon in university, as well as developing skills expected in uni more effectively and giving better UAI scaling.