Aussie Post have their problems like all shipping companies. I used to sell Flyers, magazines and video games to buyers all over the world, and I didn't have a problem. Everything I sent was trackable and required a signature. Nothing went missing and there were no complaints as buyer knew they were paying for the extra service when they bought off me.
Since I send larger items, I have an account with Fastway. They are much cheaper than Aussie Post - especially on larger items. I chose them as they send backglasses fully insured for $1500. Anything under 5kg that can fit in an A2 satchel costs under $15 - and they pick up the item. No more waiting in line at the Post Office. This is the BEST part of having an account. In my precinct, the Fastway van visits at least 3 times a day, and usually just pops his head in the door. If I have something to pick up - I simply SMS the driver.
The problem with Fastway is that you need to buy books. I've spent over $1500 in setting up for backgalsses and plastics sets. It works for me, but won't be any good for single parcel use. You can ring them up and ask for a "one off" job, or buy a book (10 stickers) - but you need different books for different locations. It does get a bit confusing, buy I'm used to it now.
Since changing, I have used Aussie Post once in 6 months.