Depends on which part of ON you are going to. Toronto won't be as cold as Queen's in Kingston, or UWO in London.
If it snows, check the forecast - if it's too heavy, school might be cancelled. For the most part, there will be snow plows clearing up most of the snow on heavily used roads. Vehicles will change to winter tires, or put chains on the tires, depending on locale. Driveways will be shoveled clear of the snow, and salt is usually used to get rid of ice. If you rent a house with others, you are responsible for shoveling the sidewalk in front of your house.
Always wear layers. Wearing one extremely heavy jacket and a t-shirt underneath isn't pleasant because you are either overheating or freezing. Wearing layers means you can always adjust - add a layer if too cold, or remove a layer if too hot. Get a toque/beanie, decent pair of gloves, and a wool scarf. You can get decent gloves at a dollar store in Canada - not very durable, but very warm. Here's another thing: cotton is a bad idea in cold weather. Never really wore snow pants - most of us stuck to jeans. Maybe leather shoes if there was a lot of snow.
For walking on pavement, put your weight on your toes (think Cool Runnings scene on the ice rink). Take smaller steps. That way, if you do slip on ice, it is a little more controllable.