Areas to take extra precaution are; railway stations or side streets at night, opportunist with favour these areas looking for vulnerable people for muggings or robbery.
As in all countries be careful of pickpockets in crowded areas like airports, city centers and train stations. These opportunists are professionals and sometimes work in teams, be aware of your belongings at all times.
Be careful when driving or hiring a vehicle in Australia as the Australian Police conduct fairly regular breath tests, drug checks and speed checks of all motorists, so do not take risks.
In public places, parks or toilets, be careful of disposed syringes, broken glass and bottles. These can transmit diseases, if your skin is pierced go straight to the nearest hospital or medical centre.