Strathfield Municipal Council has kindly offered the following comments (in blue) relating to garage sales.
 
(If there is no blue answer on a particular question, then a comment wasn't made.)
 

• Are permits required? Council does not require permits for garage sales however it is necessary to ring Council to advise of the garage sale in advance.
• Are there any laws controlling the posting of garage sale signs? The posting of garage sale signs may occur two (2) days prior to the date of the garage sale. They must be taken down on the day of the garage sale once completed. Furthermore, signs should not be erected on public land, trees or posts (i.e. telegraph poles and the like).
• Are there limits to how many garage sales one person can hold per year? Council will monitor the number of garage sales occurring from individual properties to ensure that they are not held on an ongoing basis.
• Are there laws about using the footpath in front of the person's house? Council's footpath and nature strip is public land and the use of such land is not permitted for the purpose of holding a garage sale.
• Other comments offered.
• Is there a page on the web site that covers the laws relating to garage sales?

Disclaimer:
1) Laws are always subject to change.
2) If there is any doubt, you need to confirm current council laws.
3) egaragesales.com.au provides this information in good faith, but will not be held liable or responsible for any losses or penalties incurred as a result of changes to, or misinterpretation of, current council laws as amended from time to time.