In my short experience on Ebay, I think I've learned some important lessons:

• Trust is critical. I think the rating system is very useful for weeding out those who might try to take advantage of an open bid system like this...but even with the ratings, we (buyers) are dependent on the seller to ship quickly (and properly packaged) what they say is in the lot. If I ever become a seller, that will be my goal.
• Beyond trust, it is our job as a bidder to understand EXACTLY what the seller has in mind. My first buy was a rare date Morgan silver dollar in mint condition...I thought I made a great deal until I got the coin and it turned out to be a replica (worthless). I reread the sellers description; it did NOT mention being a replica in the title, but was clearly indicated as such in the description below. That was a lick on me as a buyer! (So when I become a seller, I want to make anything like that clear up front...even unintentional, that was a real blow to my confidence in Ebay).
• Beware buyer's remorse. I have a hard time setting a max bid for a coin or collection and sticking to it (probably like most of us--we see it as competition and we shouldn't). You don't want to go higher than you can afford or think is reasonable or is contradicted by the appropriate price guide...you don't want to feel "stuck" when it turns out you won a bid. More than once I've felt "I bid HOW MUCH on THAT?" The bottomline is that you want to bid on things you want, and you don't want to bid more than the item is worth to you (economists would call it "opportunity cost"). I won an auction recently and my wife asked me how much of another, more important collection, I could have gotten for the same amount. Thanks Honey...wish you would have asked that BEFORE I hit the commit bid button!
• Have fun. 'nough said...hope to see you on the "bidding floor" soon!