Check your transfer list regularly and ‘re-list all’ as often possible
If any Kits or Managers haven’t sold after you’ve been refreshing for 48 hours, quick sell them. For all other items, consider dropping the Buy It Now price by 50 coins after day one, 100 by day two, and so on. The exception is player cards listed at 150/200: just leave them on the transfer list at that price until they sell. Eventually, they will sell. And you should be very, very rich.
Click here for more related info.