Buy a cheap van and drive it around the country. Australia is not cheap, so be prepared to spend a bit of money or earn some along the way. Get one you can sleep in and do a search on places that will allow you to park overnight.
The best way is to find little jobs you can do along the way. Fruit picking doesnt pay well, but you do get to meet a lot of great people along the way. about 6 years ago
Go on one of the organised back packer tours such as the Oz Experience in eastern Australia. A quick google should reveal different companies for different regions of the country. Many are hop on hop tours so you could possibly hop off and spend some time working given that you have time to do so and still complete your trip within the companies assigned period which ,time wise, is usually quite generous. . about 6 years ago