Heres my walking test animation kitsune, hope its okay( the arms and body are really f'ed up tho :( )

add the www if you wish to view it
.swfcabin.com/open/1254524830

Okay, I see a few things here you can improve:
-Keep the arms straighter. Try walking casually across the mirror from 1 side to another and look at your arms. They're not bent or anything, just swinging like a pendulum for balance.
-The legs aren't bad. I saw at the end you were getting faster and a bit lazier with your involvement of correcter movements. How you can help this is just doing 1 body part at a time. Just go across your whole animation with just 2 legs walking across the screen. After that add the torso, then the head, then the arms. It makes it easier to keep the same pace and make nothing look lazy.
-Your torso in this animation is perpendicular to the ground. it's straight up in a fixed position the whole time. During a walk the only person who would have a straight back would be a soldier or some other type of character like that... Keep it slightly bent more and you'll have a more casual feel me thinks.
-This is a diagram by richard williams

There is only 1 frame in which the leg is 90 degrees bent and thats the red one, the middle one, the passing position. I recommend you work off that.

Now if you take all of this into consideration and try one more time I think you'll see a better result. Again, each animation you do is an improvement. I see a clear difference between this one and your first. Keep going!

My dad downloaded that book for me, lol.
The fat shick dancing was pretty funny.

Basically do what Kitsune posted. Add easing as well.

I bought Animators survival kit a while ago before going to college and then discovered its a required textbook for animation classes.

Looks like hes doing the running man lol.