A few drills that will help you learn the basics of butterfly or improve it if you are not a beginner. You can do this drills with fins on at first.
1. Dolphin drill
Purpose: To feel the body action of the butterfly stroke while at the surface.
Procedure: Push off the wall on your front side aling the surface, keeping your hands down by your sides and looking down at the bottom of the pool. Just the back of your head will break the surface. Use your head to start the body action, push downward with the forehead to start the whiplike action of the kick. Keep the head angle changing, but primarly look down. As you push your forehead down, allow the hips to come up. Then, allow your heels to slide above the surface, and begin to kick down. Your head will become to come back up to break the surface as you kick down. Break the surface with your head and repeat. You will break the surface in the following pattern: head, shoulders, hips and heels. Keep the motion fluid.
Focus: Be sure to keep your head moving at all times. Look dow at the black line on the bottom of the pool. Remember to move with your forehead first. Develop a steady rhythm.