Have your antifreeze tested, make sure your charging system and battery are up to snuff. Wouldn't hurt to check the voltage drop between the alternator and battery, and add a new thicker fused lead if it's significant. If it's seriously cold, and you'll be there for a while, a switch to thinner weight oil will help a bit with startup and running till warm. If the truck won't hold temp while driving, string up some cardboard in front of the rad., but I'd put a hole in the center to allow for a bit of cooling, and some air flow through to the fan clutch..... If you notice the battery seems to be getting weaker, and you've been doing short drives, give it a good long drive to warm the battery up so it is more receptive to a charge.
There are other things you can do that wouldn't be worth it unless you are in cold long term. (like block heater)
