Have your wood burning fireplace cleaned by a certified chimney sweep. If you have a gas fireplace, you can also have this checked.
Check your furnace exhaust pipe often. If the exhaust freezes, it can shut your furnace off, and you don’t want this to happen in the middle of winter!
Keep your sidewalk and paths clear of snow and ice.
Keep an eye on your trees. Big dumps of snow can make trees prone to breaking (this can be dangerous if it’s in close proximity to your home).
Create and keep a home survival kit - in case of emergencies or long term power outages. This should include flashlights, non-perishable food, water, first aid kit, batteries, etc.
Stock up on salt and sand for those slippery driveways and sidewalks!
Pay attention to ice damming and icicles. These can be extremely dangerous! If this is occurring, you should contact a professional to look at your eavestroughs and inside your attic to ensure proper ventilation.
Monitor foggy windows. This is a sign of condensation as a result of high humidity. This can result in the structure of your windows being compromised. It can also lead to mould. If you see water or fog starting to form on your windows, wipe it down, turn down the humidity and monitor the situation.
If you have a plumbing fixture that is not used frequently, be sure to run some water through it (ie. turn on the tap or flush the toilet) every so often.
Check your smoke and CO2 detectors to ensure they are in proper working condition.
There are lots of other things you should be doing before winter comes such as inspecting the roof and attic, ensuring all exterior taps (and irrigation systems) are winterized, having your eavestroughs and gutters cleaned, etc. I hope this is helpful!! If you have any questions, feel free to reach out to me or contact a professional in the specific field.