So, my pipes froze in my house today, and it made me realize that I should better insulate them for the rare days that it gets in the teens here... What should I do to insulate them?
Something like this foam pipe insulation should do the job:
Source - UK site, but you should be able to source this in the States.
It's split down the length so you can wrap it round existing pipes. It's flexible and easily cut so you can do corners and bends too. You might need to tape it a regular intervals to keep the insulation in place if there's not a lot of room between the pipes and any walls/beams.