I charge them up to about 50% on my Hyperion (about 3.8V/cell). Then I wrap them in bubble wrap and put them in a large Ziploc freezer bag with a dessicant pouch. The dessicant pouch prevents condensation. The bubble wrap acts as insulation and slows down the temperature changes to prevent a part of the battery touching something cold in the freezer from chilling much faster than another part and causing thermal stress.

When it is about time to use them, I take them out of the freezer and let them sit for 2-3days inside the sealed bag and bubble wrap to come up to room temperature slowly (and so there will be no condensation on them). I cycle them once at low amps (1C charge, 1C discharge) and use them as normal.