One of the early trials of any character animator is animating a convincing walk. Here's a great diagram I found to get started on blocking it out. Notice the CONTACT pose is the extreme key. If this is off, good luck with the rest of your animation. Even though this shows a traditional 2D walk, the same principles apply in 3D. I like to get my poses locked down and check them by rendering them in the side viewport in Maya and turning on the Alpha in the Render View. This is the best way to make sure the silhouette is reading and the character is balanced.