“I tell beginners to try to read the stream and make their mends where they think they should go. Then after they have fished that lie, make several straight casts without mending to the same area. Don’t watch the fly. Instead observe the fly line and leader as the mismatched currents force curves into the line. The flyline will show you where the differential currents are, and the direction and depth of the curve shows you the differential velocity between the various currents. Now try to mend the line so that it is a direct opposite of the displaced fly line. Make a “mirror image” mend.”