First, of course pick a quality bird. A big bird as the left overs are great! I like 20lbs or so. Then, you will need a plastic tub of some sort to brind (walmart has plenty).
2 gallons of distilled water, one gallon of apple juice, cup of salt, cup of sugar, about 5-6 sticks of butter. I like fresh rosemary and course black pepper (but you can use whatever rub you want). Thaw the bird completely and trim. The night before, in the tub, add salt and sugar, pour about half gallon of apple juice and whisk until dissolved. Place bird in the tub, pour remaining apple juice and distilled water until bird is completely submerged then place in frig overnight.
The next morning, remove bird pat dry with paper towels. Using 4 sticks of soften butter add rosemary and black pepper mix with fork. Prior to this I start my smoker. Using your hand, loosen the skin as much as possible. Then grab a handful of the butter mixture and rub it over the turkey (under the skin) and inside the cavity. Also add a few sprig of rosemary. Rub the skin with mixture as well. Then place on smoker at 275. 20lbs take about 3.5 to 5 hours.
Every 30 minutes or so baste with melted butter. If (and it will) the wing tips or leg tips start to get to brown wrap the area with pieces of foil. If the breast start to get too brown, tent with foil. Once it reaches temp (checking between leg and thigh joint, being sure not to touch the bone) wrap in foil for 30 minutes before carving.
By the way I use apple wood to smoke with. Also, trust me BRIND...always BRIND!