It’s generally a good idea to keep the ram wiped down with the same fluid used in the jack. In most cases that’ll be something like 5606. That should put a stop to any corrosion going forward.
You can clean it up with 0000# steel wool, just do it lightly. Wipe it down with ATF and when you store it, leave the ram inside of the cylinder. That way the ram isn't left exposed to the elements.
Edited to add: You can use some crocus cloth if you have that on hand as well.
