Sadly you really can undo the damage. This gets into the handling and storage of the cable.
Don’t touch the connector ends with dirty hands the grime and acids/salts in your sweat can damage the finish and the grit will act like sandpaper. Use a isopropyl alcohol wipe cleaning the ends when they become soiled.
As for storage I recommend a simple sailers coil method as outlined here The trick to coiling lines Unlike a rope we don’t tie it off, instead a velcro loop tie is used. You don’t want to knot the cable just a simple round coil, held by the velcro tie.
Use a Nylon mini stuff sack or Rugged plastic pouch to hold your cables.