The below factors should be avoided when possible. After finding all your desired options are unavailable, consider using one of the below factors with your best options.
1-numerals.
2-hyphen (-)
3-NET instead of COM.
4-Three word domain name. (eg. originalwebsitedesigns.com.au)
5-Mispelling (eg. websitez.com.au )
6-Incidental words such as “the” and “my”. (eg. mywebsite.com.au)
Also, beware of unintended meanings. If you were making a website to help people find a therapist, www.seektherapist.com.au may be confusing.
If for some reason, you were considering www.petsexchange-insydney12.net.au, you should firstly remove the numbers, remove the word “in”, replace net.au with com.au, and remove or better position the hyphen. www.sydpets-exchange.com.au or www.pets-exchange.com.au are better.