How does a writer convey a character's nationality in text? For example, should an Irish character be written with a bit of a brogue? Also, how would one write an Australian accent? Or, is it simply enough to show, during the introduction of the characters, that they're from a certain country and leave it at that?

I have a character I'm trying to flesh out and I want her to be Australian. But, as I've only heard actors on television speaking the accent (Mick Dundee and Steve Irwin, for example), how do I 'write' that in a story? I've done a bit of research and found websites that offer language patterns and common words and such. But, how much is too much without the character dailog sounding as if it's been cut and pasted from such a site?

Thanks for any replies.