Question is underspecified. Are you trying to minimize the chance it develops mold, or maximize the length of time that it remains indistinguishable from the day it was bought?
For the former, store it in a dehumidifier. This should keep the mold away for a good hundred years, or however long you can keep it thoroughly dried.
For the latter, store in a plastic bag with clean paper towels preventing contact between plant and plastic.
You can also go in between - store in plastic + paper towels while keeping an eye on moisture, and if you see visible water partially open the plastic to increase air flow. Once the water is gone, close the bag again.