I add a little sugar to the brine, add fillets (skin on) and let set in the fridge overnight. Pat the fillets dry and place on a rack, to dry further. I add maple sticks from the back yard that have been soaked in water to the charcoal pan once it is hot.
Put the fillets skin side down, and add more maple or chips as needed to keep the smoke coming.
You have to tend this frequently, so a nice sunny afternoon and a box o suds and a buddy are also good ingredients.
The time required depends on how hot you keep the fire, and generally cooler and longer is better. I generally find that after about 3 or 4 hours, the fish has started to colour from the smoke, and the fat has moved up from the skin to the top. Take a taste of the fish at this point and see if it is to your liking. If not, give it another 45 minutes and taste again.
Just get started already.