Calculate your work load. If you're planning to use your snowblower just to clear a path to the front door, a single-stage model-which scoops up snow and either propels it out a chute or off to the side-is your bet bet. However, if you live in an area that regularly gets two or three feet of snow and you have a large amount of property to clear, a double-stage snowblower is preferable. This more powerful kind of blower breaks up the snow and ice with a fast-spinning auger before propelling it out the chute.
Figure out how much you can carry. As you may have guessed, two-stage snowblowers are significantly heavier than their one-stage cousins-up to 100 pounds for a gas-powered model, compared to as little as 10 pounds for a single-stage electric. If your reason for buying a snowblower is physical disability, you might be better off paying someone to clear your property rather than push or carry a huge, heavy blower around the yard.
Gauge your tolerance for noise. Gas-powered, two-stage snowblowers can be as noisy as commercial construction equipment, so if you have tetchy neighbors, try to find a relatively quiet model (you can usually find the decibel level on the box; if not, ask a salesperson). Electric-powered, one-stage blowers are less noisy, but again, they're not as efficient at clearing large amounts of snow.
Consider the surfaces you'll be clearing. Using a one-stage blower on a gravel driveway covered with snow is a recipe for disaster: the gizmo will spew rocks and pebbles out the chute along with loose snow. If your property has lots of gravel (or other loose surfaces), you have no choice but to buy a two-stage blower, which won't accidentally maim or kill innocent passersby.
Decide how handy you are. If you're the type who feels uncomfortable pouring gasoline into anything but a car, a gas-powered blower may not be the best option, since it requires regular refueling. On the other hand, you may not feel comfortable plugging your electric blower into an outside outlet, especially in wet conditions. The choice is entirely up to you.