Feed the homeless every saturday and sunday 7:30 – you can register to volunteer here:

http://www.ccn-melbourne.org/volunteer/?fbclid=IwAR1YLdeoga0oO9lFJtk9BczKUQc6OGZlont5uQ8n8THWUbtjcsIici6z7xY

You can also contact one of the organisations listed in this document:
https://www.melbourne.vic.gov.au/sitecollectiondocuments/helping-out-guide.pdf