Develop a quality catch and a quick recovery for the most power. Compare vertical acceleration strokes and lower traveling strokes. High-level paddlers strive to do an hour of flatwater drills once a week. Your best bet is to do the drills on flatwater, so you can appreciate the effects of your strokes without the complication of currents. Easy at first glance, stroke drills are hard to practice correctly.
Improvement comes with deliberate thought and practice.
Be smooth, slow and purposeful. Keep in mind these drills are just a means to an end. Get out on the river and shred it up, putting the drills out of mind. But chances are, you will find new skills creeping into your playboating.