Salmon in the saltwater feed during the slack of the tide changes. This time is normally called the "Bite". This will be readily apparent when the bite is on, because the boats around you will be fighting fish. Hopefully you will be fighting one also. The three main ways to fish for Salmon in the saltwater are Mooching, Trolling and Jigging.
Salmon have a keen sense of smell so it is important to keep smells off your bait and tackle. Anglers have been known to wear surgeons latex gloves. The easiest way to keep your hands scent free is to use a unscented soap like Ivory. Careful when you handle your gas tanks and the food you eat, they may also put the salmon's "sniffer" on notice.
You need to locate salmon to fish most effectively. King salmon will travel close to shore in 60-200 feet of water. Fish near drop offs, bait schools and river mouths. If your fishing 90 feet of water and not catching anything. Try deeper or shallower until you locate the fish. Once you find fish remember the depth and location, and fish that same area again. Don't leave fish to find fish.
Make your own reel oil. This oil smells like fish so don't spill it
How to Catch Salmon : Advanced Techniques
by Charles White
How to Catch Salmon
by Dennis Ried