I like to unroll mine, give them a good rinse then a good soak in a mild detergent, after they have soaked for a good while I take them out and place them on a dry microfibre cloth. Then take some good quality water based oil and cover then inside and out with the oil. Then after they have a good coating of oil carefully roll them up. Ensure there are rolled nice and tight and put them in a zip lock bag to keep fresh for next time.
One tip I do have is to ensure they are completely unrolled past the serial number...
Oh sorry most of you may never have rolled them back that far to even know there was a serial number