I'm not exactly an expert on writing Auspol essays because i haven't been taught how to write them. Nonetheless, i've received full marks on the two essays i've done so far, so i'll give it a shot.
Firstly, make sure your paragraphs link so your essay naturally flows. For example, if in one paragraph you were mentioning how rights are protected in the constitution you would make a linking statement in the last sentence which relates to your next paragraph. In the context of such paragraph, you could talk about the referendum process.
Secondly, contemporary examples are hard to come by and find, but they are an absolute must for any quality essay. If you are struggling or your area of study doesn't necessarily allow for such examples, you may want to use other examples such as relevant court cases or situations in Australia[s or America's political scene from the past. Perhaps you could reference areas of the constitution to support your argument i.e. S116 of the Australian constitution restricting legislation from impeding on religious practice is largely irrelevant as it doesn't prevent states from doing so.
Thirdly, kind of obvious, but answer all facets of the question. This may seem funny, but in one SAC my class did, we needed to address political parties and elections. Most mentioned elections, but failed to even remotely talk about political parties hence my class did poorly.
Yeah, that's not necessarily gold, lol, but that's all i can think of