With my own casting, I can see vast improvement when I loosen my grip on the rod on the forward cast. This allows the rod to move the line and I don't send shock waves into the line. Still, I have the tendency to grip hard and try and power the line forward.
I took my wife Atlantic salmon fishing last year for the first time and she was a great caster. I told her only about waiting on the back cast and not to let the line hit the ground behind her. Without any coaching she gravitated towards a side arm cast with stable elbow which really worked well. Later I read a column by Lefty Kreh explaining the virtues of just such a side arm cast.