Trades that you have goods enough to accept are listed first. If there are no available starred trades that you have goods enough to accept, then trades with less than two stars will be listed before larger trades with more stars that you can't fulfill. For a newer player who is a small member of the fellowship, this means that these unbalanced trades will appear at the top of the list, if the amounts requested are small enough to be in their inventory. (Smaller here is relative.)
As a new player, my fellowship members post many trades that are way too big for me and therefore appear lower on the list. The top of my list is filled with unbalanced trades for smaller amounts posted by my near neighbors. It would be annoying if I also had to deal with them from members of my own fellowship.
I mainly use the trader to post my own trades, which are accepted by my fellowship members, but I do try to look to see if there are fair trades posted by my neighbors that I can take to help them out, as we are in a backwater part of Arendyll with empty space all around.