Smoke emitting from the stove can be caused by a number of reasons, most often it’s because the flue has become clogged up. If you think this is the case, wait until the stove has cooled and pull the flue sections apart. If it looks like there’s a lot of buildup, clear it out with a wire brush or toilet brush.

Occasionally there will be some smoke upon lighting the stove, this is because the flue has not yet had time to heat up and so the draw has not reached optimum strength. Try starting your fire with smaller logs to let the stove and flue get nice and hot, with a nice bed of ash on the bottom, before you load it up with larger logs. 

Another tip is to light the fire at the back of the stove where the flue is as this will get the flue nice and hot and increase the draw. 

Make sure you are not overloading the stove with fuel, if there is not enough airflow in the stove the fuel will not be able to burn efficiently and cleanly, and this can lead to smoke building up in the chamber which will billow out when you open the door.