There are many different ways to approach a scene which contains a character walking. The first thing you need to figure out is what the scene is about. Is it a one off shot of a character walking into frame and saying a line? Is it a series of scenes of one or more characters walking and talking. I have worked on both types and many variations. When I was working on The Incredibles, I got a bunch of shots with Edna and Bob walking through her home talking about the past when he brings his super suit to be repaired. The best way to approach a bunch of shots like that was to create two really good walk cycles and plop them on a path. Then layer the acting on top of the walk. The best way to layer the walk on top is to use controls that let you animate on top of what you already have. Obviously you have to alter things like the arms in order to gesture, and the head to hit accents of dialogue, but the cycle you create is the key ingredient.
Now, what about a one off shot? A cycle is usually not the way to go, but I have seen it done well. An example of this was a shot in The Incredibles that animator Dave Devan did. It is of Dash in the cave with violet. He get up, says, “Well I’m gonna look around now” After he blocked in the character getting off the floor, he plopped in the walk cycle and showed the shot for a first pass to Brad. Once the basic idea and acting is approved, the walk cycle can be massaged so that the transition from the keyed animation to the cycle does not look bad. You never want the audience to see that the walk cycle is in fact, a cycle. You want to mess it up a bit and vary the timing of things and make it feel more organic.
The last case scenario would be the shot where you are basically keying the walk from start to finish. I am working on a shot like that now. First, I try to figure out where I want my character to be walking. You can either use a path or straight X,Y, Z controls. Then I start blocking the key poses of the walk by doing the legs first. I usually block on 4′s. I am thinking about the stride pose, the passing pose and back to the stride again. I inserted the images from Richard Williams book for a quick reference. Once I get that blocked in, then I can start thinking about the details of the push off and the timing of how the legs arrive at each key. It isn’t easy to do a good walk. In fact, its one of the more difficult things to pull off well. One of the most important things is making it feel in balance. You can only cheat so much. Your character really needs to feel like they are in the world. Once the legs are in then you can start getting into everything else like the acting, torso, arms, head, etc etc. In another post we can focus on the acting with a walk. This one is just a warm up to give you a tiny insight about how to approach 3 different types of shots that contain a walk. Again, no way is right. Its what works for you.