Too many novice flats fishermen have difficulty seeing a fish, and when they make the cast, they let go of the line. As the cast ends, they must look down to recapture the line, and when they look up, they can't find the fish. Instead, practice casting at a target and allow the shooting line to flow through your cupped fingers, trapping the line when it is over the target. During this time, never take your eyes off the target.
Once a good cast is made, listen to the guide. From his elevated position he can see both the fish and the fly. Do exactly as he says.