Many visitors underestimate the power of the sun in Australia. Even if you are not in the bush or the desert, the sustained sunlight can burn you quickly and is a challenge for many visitors. When camping in Australia, be sure to plan on carrying some extra-weight sunblock. Waterproof sunblock is best, with an SPF of 30 or above. Apply it frequently if you are sweating. Also, a good, light and breathable hat and a pair of sunglasses are essential camping supplies.
Between the mosquitoes and the flies, few visitors to Australia are prepared for how bad the insects can be. They are the worst during the dry season (America's winter) and are particularly bad in the bush and back country, but you should plan for them no matter where you plan to travel or during what season. The hats of pioneers and prospectors in Australia used to be hung with corks that would swing back and forth to startle flies away. If you plan to spend a lot of time in the bush, invest in a light mesh cowl for your face, as insects are attracted to sweat. Obviously, insect repellent is an extra weight for camping, but it must be considered. Finally, make sure your tent is well-equipped with fine mesh bug screens. You may also want to consider sleeping with your mesh cowl on as well.
There is a lot of open real estate in Australia, and there are horror stories in the papers every year about people who get lost in the bush. Especially with today's lightweight global positioning systems, there is no reason to be caught without a GPS during your travels in Australia.
Snake Bite Kit
Australia is famed for its deadly creatures, including spiders and snakes. While spiders are typically easy to avoid (always empty out your boots in the morning!), snakes are less so. Most of the snakes in Australia are shy and will avoid human contact, but there are exceptions, including the Taipan. Keep an eye out for snakes sunbathing on paths and rocks during the day and avoid them. Do not be caught without a snakebite kit, just in case.