I reckon, hands down, the best introductory multipitch route in the Melbourne area is Spiegals Overhang at North Jawbones.
Why?
it follows a clear line and isn't easy to get lost on
great gear all the way up
good belay ledges, with awesome views
great clean rock
easy enough that you can concentrate on learning the basics of multipitch rope work but still hard enough to be interesting
Get there early coz there are often parties on it. You'll need something to wear on your feet on the walk off. It will be cold up there this time of year so dress appropriately.