I want to go to Australia (some day). What advice do you have? What are must-do things?

I was in another thread, and saw this:

… So I came back to add “not in Melbourne”… except when surrounded by drunks in a busy bar (and that’s your choice anyway), you don’t have to be aware of your surroundings in Melbourne. We don’t even have a shark or jellyfish problem.

It’s still the case that if you go outback, into the country, you can get a long way away from any kind of rescue, and I wouldn’t go bushwalking by myself. That would be just stupid. But in the Melbourne there isn’t any place I would be afraid of walking at any time without paying any attention.