First and foremost rule, since I've been doing this professionally for a while: not only read but KNOW the operation manual for your snowblower. Second be familiar with all the controls (especially the kill switch) in case of an emergency. Third. make sure that the unit is NOT startable by children and the inexperienced when you're not around. Fourth, remember your limits and the limits of the snowblower, both of you can only do so much therefore keep your shovel.

Fifth, buy a snowblower that you can handle. No use buying one that is too big for you or your job. Conversely, buying a one stage snowblower or an electric one when you have mainly wet snow will be a disaster.
Psst: Thanks Df. as usual you have a good page of info. It is always appreciated.