The Australian Outback is really huge, and this has given rise to the important hand-waving rule. Because you might not see another car for hours at a time, it's polite and customary to wave at every car you see.
This is fine in the Outback, but when you get into a town it can be very hard not to continue waving at every car you see. This, however, is not advisable as it can be very hard to steer when constantly waving. As you drive towards increasingly urban areas, you might like to bear in mind the following:
Melbourne Driving Etiquette
In Melbourne there are trams everywhere slowing down the traffic and generally annoying everyone which, whilst quaint, are adept at stopping you from getting to work on time. It's generally regarded as polite if when behind a tram that is stopping you also stop, and don't seize the opportunity to overtake on the inside lane to get in front of the slow moving annoyance. In fact, more than etiquette, this is a law which is aimed at stopping drivers from running over innocent pedestrians as they unwittingly disembark.
The problem with the above is that in Melbourne nobody wants to stop. Everybody seems to be running two hours late for everything, and as a direct consequence you can never swap lanes or take turnoffs. Also, you can't ask for directions whilst stopped in traffic, because everyone is too busy swearing into their mobile phones.
Driving etiquette in Melbourne can be summed up as follows: do whatever you damn well like (except running over pedestrians), just do it with conviction, otherwise those people swearing into their mobile phones will start swearing at you. And then you'll definitely never be able to change lanes.
Perth Driving Etiquette
The masterminds who designed inner-city Perth decided that what was really needed was a whole load of one-way streets and two pedestrian malls. Therefore, if you see drivers frothing at the mouth, with glazed-over eyes, and gripping the steering wheel with white-knuckled hands, they are probably trying to get to somewhere that is impossible to approach from that angle, and are now trying to find the Town Hall so they can drive their car straight through the front door to register their discontent.
As if that wasn't bad enough, the same masterminds have just reversed the directions of many of these one-way streets. It's now quite an adventure to drive in the city because the chances of ending up where you wanted to go are quite remote, so you can spend your time trying to wipe out those pesky bicycle couriers who flit about everywhere.
Thus, in Perth, few rules apply. When parking, particularly in the parallel parking bays along the beach-front (for example, in Cottesloe) park as close as possible to the car in front of you, to make it just that much harder for them to get out of the parking bay. This is especially important if you are the last car in the long line, and have plenty of space behind you.