These are pretty cool.
One thing though, on the second image, looks like they are weak in the knees. If you're trying to make them look like their walking, do what Reno said, but also just look at images on google or something. I generally have that issue as well, and doing that helps.
In the second image it does look a bit off but what I was trying to make was that those people had been traveling in the post-apocalyptic world for a long time to get to a rumored city to have water and all the food you could eat, and when they're so tired and about to give up, the see it but it's destroyed and stuff.
Edited:
Since a lot of people like these I'll make some more today