If your hands and arms are too tight, do the opposite and hinge your wrists quickly. By exaggerating and finding the middle ground, you will improve your swing.
To control trajectory, practice using a sand wedge to hit a low shot followed by a high shot. Play around and experience this same drill with other clubs.
Work on getting a stronger grip. Hold the club more in your fingers, left hand on top, and palms facing down.
If you are having trouble getting your hips out of the way and swinging over the top, this drill will help. Practice using different clubs.