Hello,
I have many dancing costumes and items for sale, but I have posted them on many websites but they havent sold that well. Any advice??

Thank!

If there are any USA Dance competitions that are held in your area, check to see if they have a consignment rack where you can take your dresses. I've sold a dress or two that way, and the consignment fee was very modest.
Also, phone around to dance studios in your area and let them know that you have some dresses for sale. Ask them if you can post photos on a bulletin board, or, if they hold practice sessions or parties ask if you can stop by and show your dresses. I've sold one or two that way as well.
Good luck.