Pedaling is about spinning, not stepping

An excellent way to become a better pedaler is to practice a shuffle-like pedal action. This resembles the motion used to scrape mud off the bottom of your shoes.

Do the Pull-and-Push.
Each time a pedal reaches 3 o'clock, pull straight back (parallel to the ground) with the front foot and simultaneously push straight forward with the trailing foot. This action feels funny at first but if you work at it a bit, you'll find that it helps a lot, especially on hills. And, after a while you'll pedal smoother than ever because you're able to apply power through more of the stroke. This happens because the natural up-and-down pedal action is complemented by the new fore-and-after motion.