In my opinion, this is not the easiest way to animate a walk, because for each move of say a leg, the rest of the body moves to, so rather than animating parts, you should draw keyframes, and then fill in the frames between. So if you're aiming for a "correct" walk, you're making it hard for you by doing it piece by piece, since you'll need to eventually puzzle together it with corresponding movements in chest, arms, neck, head etc.