I don't have a problem with the takeoff and landing of my butterfly kick, but various people have suggested different way to perform the kick. Usually when I do the kick, I launch my lower body upwards and keep my head level.
I have heard others say to dip your head downwards more or to arch your back. When I do arch my back, I feel as though I have a little more lift and keep myself airborne better. I tighten my muscles more rather than let leap high (I have the natural ability to do so) and then let gravity take over.
Is there a "standard" to how the butterfly kick is done or is arching my back (among other slight variations) merely a stylistic difference?