Before starting your gold prospecting in Australia you should learn about gold prospecting licenses, gold prospecting rules and gold prospecting equipment.
Anyone can prospect gold in Australia. Just get a license for private gold prospecting. Every state has its own type of permit. The reachest in gold state – Victoria – issues a license valid for 2 years, other states issue 1 year or lifetime licenses. Cost of license starts with $30.
Gold prospecting rules vary from state to state. For example in Victoria only shovels are allowed, however gold detectors (metal detectors) are permitted everywhere.
One has to be aware of aboriginal cult places and National Parks where gold prospecting is forbidden.
Some states limit gold prospecting to the weight of equipment (up to 20 kg).
All the gold you managed to find - is yours! Only in NSW there is a limitation of taking no more than 30g prospected during 48 hours.
You can sell your gold to private buyers. In case of significant quantities price can be close to the market one. Nuggets are priced higher than market price.
Modern gold detectors with a high resolution allow to find gold not only in un-explored regions but even in well known locations. Typically your chances are good in plain landscapes, among trees and small rocks. River beds have been thoroughly explored and exhausted by previous gold prospectors.
The biggest gold nuggets in history were found in Australia. Many more are waiting to be found yet.