Hi there,
I mainly troll even though I only fish with flies and I rarely ever get skunked. One mistake I see trollers do all the time is to troll with a motor. This imparts a very unrealistic motion on your offering. Rowing on the other hand imparts a very authentic motion on same. I am not against motors for certain uses as in windy conditions or for going long distances on the water,but when you get to where you want to go, "row".
Also, read the water and try different depths. I always have four different types of line in my dingy or tube. I have a big heavy sink line a sinking tip line a
floating line and an intermediate sinking line,and I'll switch back and forth as conditions dictate.
If you are trolling along not getting hits, change your offering be it lures ,flies ,bait,if and when you have selected propely ,you will know about it real soon! Hope this helps