Always be sure to maintain the proper inflation for safety, performance and longevity.
Buy four matching tires, for the most part. Some rear-wheel-drive cars can get by with just rear snows, but front-wheel-drive cars should never have snows up front and non-snows out back. The inconsistency in grip during braking can cause the tail end to slide out of the driver’s control. All-wheel-drive vehicles require four tires as well.
When purchasing a set of snow tires try to pick up an extra set of wheels on which the rubber can be mounted. Not having to mount/dismount tires each season saves time and maximizes tire life. Often your dealer will sell a reasonably priced set of steel wheel to match the snow tires.