I agree with Beanz about not keeping your feet dead flat during the whole pedal stroke. I prefer to let my feet move naturally, on their own. Some may be able to keep them flat, but it's not easy, and I don't know that it contributes anything to pedaling efficiency. I'd rather concentrate on "pedaling circles."
I know the subject of "ankling" can be a hot button, even to the extent that many don't even agree on a definition. But simply not keeping your feet flat is not, to me, ankling. I've always understood the term to mean consciously rotating your foot from a flat or toes-up position at the top of the stroke to a toes-down position at the bottom, so that you engage the muscles of the lower leg to help drive the pedal down during the power stroke. That particular practice, whatever it's called, has been pretty well determined by the scientific types who study the pro peloton to be ineffective at best, and injury-inducing at worst.