According to the Australian Post website, addresses should be written as follows:

1. The top line should contain the recipient’s name
2. The second last line should contain the number and name of the street, or PO Box or locked bag number if applicable
3. The last line should contain the place name or post office of delivery, State or Territory abbreviation and PostCode. This line should be printed in capitals without punctuation or underlining. For overseas mail the country name should be in capitals on the bottom line.