Here is a frustrating problem that I often encounter in my casting:
My cast hooks to the left instead of going straight out (I'm right handed). In the worst instances the leader will end up 90 deg. to the line. I try to keep rod motion in a straight path as best I can, but that doesn't seem to help. There seems to be too much kinetic energy in the cast which ends up dissipating itself by turning left. To try to stop it I will sometimes place my right foot forward instead of my left. This reduces upper body rotation making the cast somewhat straighter, but its not the total answer.