I just sold several items I listed on there. What I found worked for me was timing (which is just coincidence) and pricing. You can't really go at it expecting to make a lot of money. I just price items to move (anywhere from $10 to $25 - even for top of the line toys) and then they move.
At first, I went into it hoping to make some money, and then I decided it was more important to just clear out the space and get rid of the stuff. Once I decided that, and priced my items accordingly, I sold all of them but 2 the very first day! (And I did end up making a little bit of money that way.)
Plus a lot of it is timing, which we can't know ahead of time or control. If you happen to list something that someone else happens to want, then it will sell.
PS - If you didn't already know, you can check and see how many "views" each of your ads have gotten by clicking on "My Ads" in the upper right hand corner.