I have a "Foodsaver" (vacuum sealer) that I use with the block. I'll open the bag, cut off what I think I'll use either immediately or within the next few days, and then vacuum-seal the bag again.

Before I had that, I would usually wrap the cheese in a layer of wax paper, followed by a layer of foil, and put that in the freezer, taking it out as I needed it. Hard cheeses in the freezer will turn white and may no longer be useful to eat shards of on their own, but they're still fine for grating and melting.