I buy and sell on eBay. The primary rule I follow is the Golden Rule: Do unto others as you would have them do unto you. This includes trying to resolve issues privately rather than through the feedback system.

When I sell, I leave feedback for a fast- or timely paying buyer as soon as s/he pays me (except when I suspect the buyer may be trouble). Then I do my best to provide excellent service. I view the immediate feedback as a feel-good inducement for the buyer to leave me positive feedback, which I'm already confident I will deserve. I also like to get the feedback out of the way so it's off my List of Things to Do.

When I buy, I pay very quickly -- usually within minutes after end of auction. I am always annoyed by the seller who waits until I post feedback first. My perception of such a seller is that s/he is either stingy at best or potentially retaliatory at worst. Nevertheless, if the seller provides good or excellent service, I leave positive feedback. But I must admit I am always reluctant to leave neutral or negative feedback, and even if such feedback is well-deserved, I usually leave no feedback rather than risking retaliation. (I have seen buyers who post mere neutral feedback receive negative feedback in retaliation.)

I do like the idea of having a double-blind feedback system. I have no doubt there are many eBay sellers who have overinflated feedback ratings due to real or perceived fear of retaliation.