Getting back into fly fishing only several years ago I can feel your pain, however just remember what they say,"A bad day fishing is still better than a good day at work." I'm far from being an expert on ready the water and most of what I know is from trial and error (and the great info I've gotten from this site). However the most important thing I learned is to be flexible in my approach to fishing a body of water (river,pond,ect.). If you find a spot you think fish are holding up don't rush to it but fish your way to it, including places you don't expect fish to be. Sometimes the places were you don't expect fish to be are exactly were they are. Now I'm not saying go out of your way to fish these spots, but there is no reason not to cast to them while you approach the spot you want to fish. The same goes for presenting your fly. If nothings taking it, before you try a different fly or different location change the way you present it to the fish (even if it's not the 'proper way') sometimes it works. When the fish aren't bitting it's the perfect time to experiment.