I brine mine with a rub mix of salt and brown sugar for 12-24 hours. Then rinse and let them dry. I apply a bit of brown sugar, garlic powder and pepper before going on the smoker. I smoke around 150-175 until I reach 140 internal temp which is usually around 4 hours.
I don't like mine with as much salt and sugar. I brine with salt and a little molasses for 1-2 hours depending on the size. If it's a full inch and a big piece, maybe a little longer. rinse well, and let it set until it forms a pelicle (?spelling), ie until it feels tacky.
I personally dont brine salmon... I do use brown sugar and some old bay seasoning..On my vertical i use the top rack and smoke at around 250 till the fish reaches around 135 ( just starts to flake with a fork in the thickest part)..Low and slow doesnt really help much with fish..I try and use a light wood with fish , like alder.. Happy smokes !!1