Finding these angles becomes intuitive. Without thinking much about it, I usually set myself up with the sun behind or to my side, avoiding the surface glare of direct light. As I fish upstream I might work left bank to right, moving perpendicular across the stream flow until I reach the right bank. Then I quickly wade left again, back to the left bank, to start over on the next line — like a classic Underwood typewriter printing out one sentence at a time, just to see into the water, see my fly or watch my sighter . . .