The type of salmon you use is also important. Sockeye has the best flavor an oils in it for a really good smoked fish IMHO. All smoked salmon is great, every one has a different flavor profile, but Sockeye seems to come out the best. I use alder for fish. Different woods would also taste different. Rum is good too.
CURE:
2-3 lbs. fresh whole boneless salmon fillet.
Approx. 1 1/2 to 2 cups dark rum (e.g. Bacardi or Cruzan work well)
1 cup brown sugar
1/2 cup kosher salt
2 Tbsp ground black pepper
Directions
Cut the salmon fillet(s) into manageable portions, then skin them if desired
Put in a glass or non-reactive dish and cover with dark rum (no need to measure the rum; you just need to cover the fish so it coated all over). Cover and refrigerate for at least an hour, flipping the portions halfway through (so both sides are well marinated). You can also prick with a fork to get more rum into the fish.
While waiting, make the rub by mixing the brown sugar, kosher salt, and black pepper.
Drain the rum and pat dry the fish and the container. Spread a third of the rub on the bottom of the container, then lay the 1st layer of salmon on top. Spread another third of rub on top of salmon, then lay last layer of salmon followed by last of rub. (If you only have one layer of salmon then split the rub into halves vs thirds). Cover and refrigerate 8 hours.
With enough time prior to finishing the rum-soak, soak your wood chips (I recommend apple and/or pecan) and get your smoker started to bring it up to 150F. Rinse salmon in cold water to wash off most of the rub (the cured salmon is the prize, not the layer of rub) and pat dry. Put in smoker, add wood chips and smoke for up to 8 hours at 150 degrees. Go by internal temp as fillets differ in thickness.
Remove the salmon from the smoker and let it rest under a tinfoil tent for 5 min and dig in.
I, personally, have played with the temperature, (1.5 to 2 hours @ 225 degrees). I have left the fish in the rum for 24 hrs and with the rub another day. Have at it. Good condiments are sour cream, sliced red onions, capers and fresh dill.