The problems I've seen most (aside from the casting) is that people don't get the fly down deep enough when fishing subsurface and they don't pay attention to drag on their fly.

As for hatches, I always heard that insects generally hatch during the most pleasant part of the day.

But you may very well be on some tough water. Here's a site I like for hatching of specific species: [url=http://www.westfly.com/ento/ento.htm:7f195]http://www.westfly.com/ento/ento.htm[/url:7f195]