Lots of really great information and observations here. Great thread. Sure helps a "regular" guy like me.
However after five years of fishing Sooke (not much maybe compared to the experts on here) I do have an opinion. I think Profisher's original point #3 in the first post is the most important and should be #1.
Being at the right location on the right tides is key and is the main reason many are more successful. I still do not really know when to fish where. (I'm talking about just Sooke here where fish are fewer in number than say Haida Gwai, Swiftsure or Nootka and exact location is maybe not so important).
You can have the most reliable and fishy roll, the sharpest hooks, the best knots, and invisible fluorocarbon leaders but you still cannot catch a fish that is not there. In Sooke it is about location, location, location and you can only learn that by experience and keeping a detailed log of what fish were caught where and the state of the tide at the time. Patterns may then emerge.
I keep a log but I have not been able to see any patterns yet. Last year it was the Bluffs and Sheringham that produced a few for me. This year it is harbour mouth and Possession for the small number I have caught. I have no idea why. Until I work some more of this out and understand where to be at what state of the tide (and what area to troll) it will remain a bit hit or miss.
P.S. Smell may be important as well. We humans have an amino acid on our skin called L-serine and salmon have been shown scientifically to be very sensitive to it. Here is a link to a paper but there is a lot more on the web about this.
http://jgp.rupress.org/content/39/6/889.abstract
As result, I always bait up using gloves.......