We often hear the quote that "90% of the fish are caught by 10% of the fishermen". It is probably close to the truth. Did you ever notice how the anglers who are really 'lucky" also seem to have a wealth of experience? One angler who I had the pleasure of fishing with, always would give the same answer to the question "What did you get them on John?" He would reply "Skill, and a wee bit of luck." John wasn't being a smart ass he was just saying he had done his homework.
Fishing is definitely an art and some are Masters. Trolling is a great way of covering a body of water, the trick is fishing the productive areas of the lake or ocean and not wasting time on the less productive regions. Do your homework. A depth chart of the water may be obtained from the Angler's Atlas or Go Fish BC At these sites you can also find lake info, stocking data, directions, special regulations and the very important depth charts. The depth charts are the key to finding the dropoffs, shoals, reefs, points and structure that the fish need. If the lake is an old friend you may already know the "hot spots" but when fishing a new lake the depth chart is invaluable.
Fishing where the fish are seems obvious, but many areas of the lake do not hold fish. A fishfinder lets you know for sure that you are in the zone and what depth the fish prefer that day. It is no use trolling at 10 feet if the fish are at 40 feet. Depth control is critical. The fish may be stratified at a certain depth for oxygen, comfort or feed preferences and if you want success you better be in that area. Downriggers are the best means for achieving exact depth but you can also use Deep Six or Pink Lady trolling planers, metered line, line counter reels or the old count the "number of pulls" method. Not all fish will be picked up by your fishfinder as fish very close to the surface will move away from the boat and won't be picked up by the cone angle of the transducer. That is why we usually have one rod working shallow.
Give the fish a choice. Once you have the depth vary the offerings to see what they prefer that day. For example a Flatfish on one side with a spoon on the other. Make sure lures are compatible, some lures work better at different speeds. Don't mix them up. Adjust speed of boat to get optimum action from the lure. One lure that works at any speed is the famous Rapala minnows, which hold more world records than any other lure.
Make sure your hooks are "sticky sharp". Make sure your hands are clean of offensive odors such as gasoline, insect repellent et. Carry a good biodegradable soap along and keep those hands clean. Use fish attracting gels or scents where legal, if targeting bigger fish, they definitely work.
Most of the trouts insect diet is migrating from deepwater to shallow at this time of the year. so when trolling don't just parallel the dropoff but troll in lazy "S" curves across the dropoff. You will cover more water and depths this way. Keep track of the rods as the inside rod will slow down and drop while the outside rod will speed up and rise on the turns. Which do the fish prefer?
Many anglers have a lot of success by taking the motor out of gear once in a while and letting lures drop and slow down and then kick motors back into gear. At times this really triggers some fierce bites.
Avoid the noise. Fishing is supposed to be the quiet sport. You would never know that on some lakes. The tin boat really amplifies sounds and the shuffling of feet, tin cans rolling around, anchor chain moving, kids drumming etc sends a loud and clear message to the fish to steer clear. Did you know that sound carries 4X better underwater than above? That is why many anglers carpet their boat, easy to take out and hose off too.