I cannot stress enough how important this is. A strong, no questions asked, guarantee will reassure your buyer that he has nothing to lose by bidding on your item. In my opinion this is the most important paragraph of information in the whole listing.

In my experience returns are virtually non-existent (less than half of 1%) so don’t be afraid to offer the strongest possible guarantee, it will make a huge difference to your final values.

Something along these lines is very effective;

Buy in confidence, no quibble guarantee

I will refund your full purchase cost plus postage if you are not DELIGHTED and the item is returned undamaged in it’s original packaging.