Internationally it’s the thumb, but here on the Monaro, it’s the forefinger or index finger. This gesture will distinguish you as a local in Australia. Carry a destination sign… this will improve your chances of hitching a lift. And if , on that sign, it shows “$ for fuel”, then it may increase the chances even further. The link below gets you in conversation terms with the driver:
https://www.facebook.com/groups/162771967688/