Make sure you buy four tires; skimping and putting winter tires only on the drive end of the car will result in unpredictable handling and could be dangerous.
If you’d rather not remount your tires each season, pick up a separate set of inexpensive steel wheels for permanent winter-tire duty. This also keeps expensive alloy wheels from getting damaged in harsh, salty winter conditions.
Swap to winter tires in November and back to all-season or summer tires around Easter–winter tires’ softer rubber compounds wear quickly in warmer temperatures.
Store off-season tires in a cool, dry area out of the sun, and consider wrapping them in black plastic bags to reduce oxidation.