This is the cheapest and most flexible way to get around in Australia. It is a bit more expensive than car hire, but it saves you the cost of hotels/motels, and also you can cook your own meals instead of eating out. Compared to buses and trains you get much more freedom to stop wherever you want, and it is much, much, cheaper. In other words - it is the best way!
Courtesy of Tourism Queensland
Your best bet is to choose from the big companies such as Hertz, Maui, Thrifty, Britz, Apollo, Avis and Europcar. They may be a bit more expensive than the real budget ones such as Wicked, but they are way safer, have services in bigger towns, and can be called up when there is a technical problem. Unless you are really good at fixing mechanical problems, the last thing you want is to get stranded in the middle of nowhere and have no-one to call to help. Wicked campervans - the bright coloured ones in hippie paintings - have shown such poor quality that they were banned in some states at one stage (not sure if they still are).
NOTE: This website is written in British English, which is the English we use in Australia. You will find words like "traveller", "harbour" and "realise", and they are all correct in the language used in Australia.