I guess it depends on how many 'good' sales you have to balance it out.

If tracking shows as delivered then as others have said, you need to upload those details into the dispute.

The only other things I can suggest is maybe limiting sales to Australia only.

Plus always having tracking. The neutral i can see in your feedback says the item, valued at $55, had no tracking. At that price point, I would not risk it without tracking.

I don't know how common buyer scams are but I suspect they are not as likely to claim item not received if they know there is tracking to prove otherwise. (Or so I would have presumed anyway)