When taking your cartridges to be refilled it is a good idea to wrap them individually in tissue and put them in a plastic bag.  This avoids any possibility of them knocking together and causing damage to the sensitive electronic components.

It is also good advice to take them for refilling promptly.  Leaving them lying around in a drawer for weeks is not advisable.  The longer you leave it the smaller the chance of a successful refill.

Your cartridge refiller should clean and repackage your cartridge after testing it, we certainly do so there is no risk of damage on the way home.  However when you remove it from the protective packet be sure to only hold it by the plastic casing.  Touching the copper circuitry can cause it to malfunction.