Winter/All season tires
Here in NS it is recommended to use special winter tires for winter.
You could get by with all season tires,and many people do, and careful driving - but all the local taxi drives use winter tires. So think about that.
So here are a couple of tips
It's cheaper to swap the whole wheel compared to change tires, labor wise(each tire will set you back about 15$). So having a set of rims for each season can be prudent in the long run.
One thing to remember is that there are 2 types of rims - alloy and steel.
And a different type of bolts are used for each one.
So - if you have 2 types of wheels(steel for winter and alloy for summer for example), you should have 2 sets of bolts as well.
Studded winter tires
Some winter tires can be studded with metal studs for better traction on ice.
The downside of this is lower fuel economy and more noise.
One thing to remember - only new tires can be studded for a regular price.
Studding a used tire is costs double as you need to clean each hole before putting the stud. Which makes the whole process less economical.
Take this into account if you plan to buy used winter tires.