1. The longer the kayak, the less is sways from side to side. If possible, choose a longer kayak.

2. Stroke as close to the boat as possible. If the paddle goes into the water further away from the boat, it'll make it veer.

3. Little strokes are better than big strokes. Any time the paddle blade is in the water and behind you, it is counter-productive.

4. Don't over steer.

5. Don't over correct over steering.

6. Find a point far away and make that your target. Whenever the boat deviates just the slightest amount from going directly at your target, correct it a tiny amount with a stronger stroke on that side.

hope that help