How do I winterize plumbing in areas that are exposed to cold weather?

Depending on what kind of plumbing it is, the most effective way to winterize plumbing is to turn the water off, open the plumbing faucet/valve/etc., and use air to blow the water out of the line. If you don’t use air, then water will likely get stuck in the line, eventually freezing and bursting during the cold weather. That will invalidate all your work.