If you want to keep your options open career-wise, Arts/Law is the best idea.
If you want to be a journalist, it's probably best to do a specific journalism course. RMIT and Monash both offer the Bechelor of Communications. From what I gather, RMIT has an especially good reputation for this (although perhaps someone else can share their expertise on this).
If you are looking at straight arts, the universities that offer the subjects you most want to do will obviously be best. If you want to do something that is quite general and is offered everywhere (e.g. languages, literature, philosophy, etc.), choose the university that has the most interesting looking courses in that area and a good variety of courses in that area (hint: it's no good if you want to major in literature if the university only offers courses in literature from a certain era, for instance). If you don't know what you would like to major in, choose a university that has a good variety of courses and (more importantly) choose a course which allows for flexibility in subject choices.
If you don't particularly want to do law, Arts(Journalism) and Science double degree could be really good for you:
http://www.monash.edu.au/pubs/handbooks/courses/2131.html You major in Journalism for the Arts component and in Psychology for the Science component. Or, you could do straight Arts, majoring in Journalism and also doing Psychology courses as electives.