Before you register your .au name, make sure you have either an ABN/BN/ACN, otherwise your application will be rejected.

It be entitled to register an org.au name, you have be a registered charity, not-for-profit or non-profit organisation or an incorporated unitity.

com/net/org/info/biz names come under no restrictions however most 'dictionary words' and combinations have already been taken.

Keyword domain names should always be considered as your first option if available to help with your search engine ranking.