The walker has a neat use of contrast, soft outlines and all
Then the cagu has super harsh black outlines, bad use of colours, it doesn't look like a round body at all, rather a super thin oval.
What you need to do first is keep up style constency. Modify the cago to 'compete' with the walker, before you start fixing any other errors.
In the walker I can see a lack of anti alias in the leg 'pins' as well as that the leg to the (viewers) far right has the cylinder above the pin completely out of perspective or at a wrong angle.