Ranking on .com.au from other countries websites
If you are making a .com.au website or then trying to rank a other .com or country domain websites then to do the following:
1. Register a .com.au domain name (you can do this if you have a global trademark)
2. Build links from .com.au website (avoid link building from other dot domains to get ranking faster)
3. Build the content AU targeted on the .com.au micro website.
People try to rank .co.uk sites it simply does not compete with the power of .com.au domains or even GEO targeted .com domains.