Depending on where you are geographically, you might want to use extra insulation for your hives during the winter. Depending on your hive type, the winter covers can look rather different. A main aspect you have to keep in mind is that the ventilation in the hive should not be hindered by the insulation. Otherwise moisture will collect in the hive and this can easily lead to diseases.
If you use mice guards, you can add those during the same visit to the bee yard.