Once the brisket is placed on the smoker, make sure there is good airflow around all sides. This will give an even smoke contact. Also, when you put the brisket on the smoker rack, push it together from all sides. As meat cooks, it shrinks. Failure to compact the meat, might cause it to stretch out on the smoker rendering a tough or dried out brisket.
If the smoker heats to the side, I recommend placing the brisket fat side up. If your smoker heats from below, then I suggest you place the brisket fat side down (see Brisket - Fat Side Up/Fat Side Down?).
It is best not to move the brisket too often. I recommend that if you need to rotate or flip the brisket that you do so no more than every two hours. When you do move your brisket it is a good time to apply some mop(or baste) to the meat to replace any moisture lost during moving.