The choke on a gasoline-powered snowblower engine is designed to help the motor start when it is cold. The choke works by shutting the air intake to produce a richer gas mixture in the engine's combustion chamber. Operating the choke can be counter-intuitive, especially if it's been six months since you last used the equipment.
Set the choke on full (which means closed).
Start the engine according to the manufacturer's instructions, including three to four pumps on the fuel primer before pulling the ignition cord or pressing the starter.
Decrease the amount of choke slowly over several minutes by adjusting the choke lever until the engine warms up.
Open the choke all the way once the engine is running smoothly. Do not have any choke once the engine is operating normally; this will cause excessive fuel consumption and may flood the engine, causing it to shut down.