When you are sending parcels to Australia that will amount to more than a box or two to a relative or friend, it is probably best to use a professional service. Australia has very strict quarantine guidelines that must be adhered to, and a large shipment may be tied up for months if it did not follow standard procedures.
Professional services are aware of the strict guidelines that have been set forth by the Australian government and can easily comply. Using a service like this will make sure your packaging materials, both inside and out, are in compliance, and that all Customs paperwork is correct.
Using a service will most likely reduce your costs to ship these items because of bulk discounts and private freight moving costs. Professional packaging will help reduce damages that could occur when moving goods over such a long distance.
I wish I would have thought of this before I mailed everything off to Australia.