I haven’t made it to Australia yet but I did make it out to the Cook Islands in Oceania.
Trips to this area of the world involve long (expensive) flights, so plan to stay for awhile. Don’t have a lot of extra money after the flight? Volunteer at a hostel, they will let you stay for free in return for 4-5 hours of work 5-6 days a week. It’s a great way to cut down on the cost. You can also couchsurf with people and stay at their homes for free. Be sure to do you homework on your host and be safe.