Nice work with these, I think the biggest thing to point out is the perspective on your cube work. It can be quite tricky to wrap your head around at first, but all of the lines should be pointing to one point (vanishing piont) for one point perspective, and one of two points on two point perspective. On your cube piece the lines are mostly all pointing to different areas, making it seem like they are many different perspectives.
I would recommend drawing your horizing, and drawing your vanishing points on the page. Then if you are having trouble drawing a straight line, use the ruler tool to make sure they are straight. If they are curved it makes it appear like a distorted lense. I have provided examples of how I would set up my scene for 1 point and 2 point perspective. Hopefully this is helpful! Keep it up.
