There are certain sections in the stream where the fish are holding, so you can be catching fish on almost every other cast, while your neighbor will be skunked. Your location is very important, If the action slows then move and cover more water. Keep moving until fish are located. Trout can easily hold in depressions as little as 6 inches deep. In flatter sections of the river, this might be their only cover.
Proper drifts are also very important.
The ability to present a natural fly relies upon mending the flyline so the fly drifts naturally with the current. Flyline caught in fast current will pull the fly out of the strike zone, and give an unnatural appearance. Though, there are situations when this is the exception when fishing emerging flies. As with bait fishing, the idea was to have the baits float with the current, but directly off the bottom. The sow bugs and glow-balls were used in the same manner only using a small pinch weight.