I had to lookup this unit as I wasn't familiar with the Brand. We have numerous kitchen utensils with that brand but was not familiar with any grills or smokers . I was to happy to see that the design is the always reelable bullet type design.
You've got 2 great pieces of advice above.
1. Use water in your pan on this type unit. The water heats up from the charcoal below and that big mass of heat makes your unit stable with less temperature swings.
2. Dave gave you awesome advice on how to light a fire and a method for longer burning and less fuss in making sure you have enough fuel without adding extra charcoal during longer smokes.
A couple of things I'll add are:
Don't overload the smoker. Too much meat will actually lower temp and effect the burn of the charcoal. Remember the airflow needs to go up on your unit. If most all of the grate is covered with meat, airflow will be restricted and the fire begins to go out.
The lower vents should be wide open and control your temp by the vent on the top.
Make sure that your charcoal is well lit. Give it some time before you start cooking. Don't get into a rush. 50% of the fun is cooking!
Lastly... and maybe most important. If he is judging the smoker temp by the thermometer on the smoker then be advised that it could be inaccurate. Many suppled thermometers on grills and smokers are off by as much a 50 degrees right out of the box! This is one item the manufactures tend to cut a corner on.
Most of the folks here use a Maverick digital thermometer to judge the correct temp of our units and the meat.
Best of luck