You want to adjust your smoker to hold a temperature around 225 degrees F (107 degrees C) for the whole cooking time. Remember that your brisket is going to need to cook for somewhere between 1 1/2 to 1 hour per pound. Not all briskets are created equally so the cooking time is going to be variable. Also, wind, outside temperature, and humidity will play a big part in the cooking time so be prepared to adjust accordingly.
As for smoke, it is more important that you have a good supply early. When the brisket goes on you want to add wood to generate smoke. Meat absorbs less smoke the more cooked it gets so most of the smoke flavor will enter the meat in the first two hours than the last four.
