Big Bear hit it on the head.
I'm in Seattle, he's in Oregon, my Brother-in-law in Alaska, so what I find compared to how we like to do it in the Pacific Northwest (light salt brine, and short brine period) is soooooo many people "Muck it up" with tons of garlic and onion powder, and soak things overnight........you really lose the light texture of the salmon flavor and turn it into a too salty rock hard salmon slab. To each their own, but in Seattle and Alaska we live on salmon!
So I go very light, maybe 1 cup of salt, 2 cup of brown sugar, 2-3 gallons water, thats it folks! Maybe a 1 hour brine max, more often 30-40 minutes is all. Fresh fish takes up the brine very fast. Don't go overboard! I've ruined too many batches of fish brining overnight with too much salt/spices when I was a noobie salmon smoker. You can always add flavor later, but you can't take it away.
Pat it dry, let it skin over with a film, then low and slow smoke for 4-6 hours, don't over do the wood chips either, nice light and delicate. ALDER WOOD or Apple, pecan. Anything like Hickory or Mesquitte is too harsh an acrid smoke INHO.
Sometimes some fresh ground pepper sprinkled on towards the end of the smoke.
See photos of my last trip to Ketchikan. 8 Silver Salmon caught yeilded about 60 pounds of fillets. God gave me a wife that can fillet and not be Conan the sword weilder like me. Light quick brine, light smoke, then we even put in Kerr Mason canning jars for about 30-40 minutes through a pressure cooker to flash cook and can them. I've had 4-5 year old jars that are still excellent and moist, no vacuum packing or freezer burn to worry about.
So your method may vary, but that's how we do it on a large scale in a 60 pound batch of fillets