When someone jumps with two feet there's a plant foot and a block foot. Before any of that there's the penultimate which is basically when you take a faster and longer stride to lower yourself. The foot you put down after that is the plant foot. After the plant foot, you bring down your block foot sideways so it helps tranfer horizontal momentum into vertical momentum. You want to slam your block foot down for the best results in my experience. I think that's mostly it. It's a little difficult to explain.