"S"hooks, Command hooks or just on nails. If you've got a bunch, make a pleasing grouping on the wall. I don't like them hanging from a pot hanger from the ceiling as it cuts the room making it look smaller.
Hi Tammy although I don't have any I found this article that I thought was helpful in the details.
Good luck with your project
Hello Tammy and happy new year to you! Take a look at these links for some great information on how to hang your pots.
I would put black pipes on a board on the wall for shabby chic look with the cast iron and use S hooks to hang them on the pipe. Tammy, depending on your decor you could also use a nail or even coat hanger for each pot on a stained board. I think they look really nice hanging in a country kitchen.
Given the weight of cast iron, I'd hang them only mounted into wall studs, with very secure hangers where the action of repeatedly using and hanging them up again would not damage the wall's surface.