You don't want the trout staring into a bright glare, even if that means the shadows are well behind it, and yourself. On the other hand, you should be sure to outcast your shadow when the sun is behind you, because a fish will still be spooked in flat light if it senses the motion of the line. When it comes down to it, analyze, but don't overanalyze—just know where the sun is, and where your shadows are. And know where the fish will feel more comfortable looking up, and take it from there. Just a little bit of understanding of the sun and shade will transform your fly-fishing game, probably more significantly than most anglers realize.