Seller Protection On Ebay

Hi all. I am a new ebay seller (first time selling) and I recently listed a small lot of assorted Canadian silver coins for ~$350. As far as shipping goes, I understand it is imperative to have tracking, signature, and insurance on something of this value. This will protect the seller when the buyer claims they never received the shipment.

My question is, how is the seller protected if the buyer says nothing was in the box, or that there was only a useless item inside instead of the coins? It seems to me in any SNAD case, the seller is the one taking the risk as they cannot prove what was inside. I have read several stories of cases where new sellers with no feedback ratings are taken advantage of this way.

I would appreciate any tips from fellow members on the must do's when selling items. What is the $ value threshold where you require tracking/signature confirmation? What are the most important things you must do as a seller to prevent fraudulent buyers from taking advantage of you? Also, if the item is shipped without tracking (on low value items), will they always side with the buyer if they claim non-delivery?

Thank you in advance!