Look for the snowflake:  To reduce confusion between tires that are all season or mud and snow, the Rubber Association of Canada developed an icon of a snowflake set against a mountain.

Replace all four:  Don't bother with winter tires unless you are prepared to replace all 4 tires.  Replacing only tires on the drive wheels can cause uncertain and dangerous handling,  increasing the likelihood of loss of control in slippery conditions.

Mixing tires with different tread patterns, internal construction and size degrades the stability of the vehicle and should be avoided.

Winter tires have thousands of tiny cuts in the tread surface called sipping.  These sipes provide extra bite on slippery ice surfaces.  All season tires work reasonably well but once you have tried a good winter tire, your confidence level in winter driving will increase.

As a tire wears, snow traction is reduced:  Tires that are worn close to the read-wear indicators have reduced traction and should not be used on snow-covered roads or in severe snow conditions. 

Some provinces still allow studded tires during selected months and they work well provided the tires are in good shape but they are noisy and hard on pavement.  In fact, winter tires with many sipes outperform studded tires.

Most people install winter tires to avoid taking the ditch or avoid getting stuck However, the greatest advantage is accident avoidance.  The extra traction provided with winter tires works equally well for stopping and accelerating.

The most dangerous road conditions occur right around freezing temperature.  Develop a sense of great delicacy in control applications.  The recovery phase of a skid usually needs to be done more slowly on snow, since there's less stored energy in the springs. 

Under inflated tires:  With the high prices of fuel, tire pressure becomes even more critical to the pocket book.  The rounder the tire, the less energy it requires to roll.  Tires that are even slightly below the recommended inflation pressure can reduce your mileage by up to 10 percent.  If you do the math, that comes out to a lot of savings over the course of a year.  Almost three quarters of drivers have under inflated tires.  Large swings in temperature over time reduces the pressure in tires.