Re: help with cast
Since you said you snapped off some flies without snagging into the tree behind you, I assume that you were also hearing a "whip-crack" sound in your backcast? If this is the case, slow your cast down. Watch your backcast unfurl before accelerating to a stop in your forward cast. You may be overpowering your forward cast as well, or not having a solid stop (both would cause the pile in front of you as well as depriving you of good loops). If possible, try and get a video of your casting stroke, as we have some pretty solid casters on here that could diagnose what you're doing.
Working out a way to convince my university to allow me to hold my TA office hours on the nearby creek...