Buying cheap equipment- you get what you pay for there is a difference between a good value and cheap.
Not using the right amount of fuel for the task at hand
having your unit setup improperly
Trying to cook difficult items like brisket before mastering your grill- start small and simple
Opening lid too much- if your lookin your not cookin
In the same vein as last one over tending- trying to adjust vents too much too often
Weber performer, Smokey joe, Weber go anywhere. Mini-wsm, WSM-Soon