In addition to all of the suggestions so far, if you haven't done so yet, get schooled at Salmon University .

Soak it all up and apply it on the water. The info on that site is right on, the setups, the areas, the seaons, etc. Check out the "Ask the Pro's" page specifically. Some of your trolling questions are answered there.

Another excellent way to learn is to spend the money and go on a charter that uses downriggers. Ask questions and observe. Many times the skippers are happy to bring you up the learning curve. Even if they are not, you can still observe. It's helped me a lot over the years and it's fun to let someone else do the riggin' and you get to catch the fish! IMO, it's worth the money when you're just starting out.