G'day.
Once you sign up with the Perth Mint it's quite simple.
I just watch the prices on their AUD charts and buy when the price is right for me.
http://www.perthmintbullion.com/au/default.aspx

You can see all the prices prices and can buy either bullion or coins here:
http://www.perthmintbullion.com/au/View-All-Bullion.aspx

When you place an order they give you all the shipping and insurance options - very simple.

Hope this helps.