Hi, I live in Sydney but don't worry, you should make friends quite easily in Melbourne. Australians are used to getting vistors from overseas and most are friendly. Of course there are bad people here just like everywhere so just ignore them (we do!).
If you are going to school/uni or work then you'll have no problems. If you're staying in hostels then you'll meet people there too. Otherwise consider joining some sort of club - I'm sure there'll be tennis clubs near you as most Aussies are sports crazy.
As for how we live, we spend a lot of time outdoors, even in winter. People are from many different backgrounds so lots of things are "the right thing" to do and you can get almost any food you want. Melbourne people love a fast-moving brand of footy called Aussie Rules and you'll be arriving at the height of the season so make sure you go to at least one game!
Good luck and don't be afraid to tell people if you want company, most Aussies wouldn't think that was strange at all.