If freezing temps you just have to watch for any place that water can get trapped and expand. Pumps, Bait wells,hoses, engine blocks, puddles on deck.
Remember 32* on land won't be as cold as 32* on the water that is still open and not frozen.
Small places that water can freeze inside of are the biggest areas to watch, or drain if you don't need their use.
Salt water freezes at 28 degrees, fresh at 32 and brackish somewhere in between. Plug off your engine room intakes to keep that chill out of her, just be sure to open them back up when you're going to run the engine.
You can always rocket a gallon or two of cheap windshield washer fluid down the raw water system if you're concerned. Not the stuff with de-icer. That stuff is bad mojo.