From what I can tell you're going in the right direction. Some of the more obvious problems I can see are

1) some of the lines are drawn multiple times or look fuzzy. Do each line only once, even if it is wrong. Repeating lines like this only draws the viewers attention to them making the mistake more obvious. Make a dot where you want your line to go and try to hit it. If you miss it do not try to correct it..

2) Some of your edges do not converge into the right direction. The first box on your second page of the upload (Upper left one) but also the one next to it (upper right one) Have the orange lines converge towards the top. Some also go almost straight up. Consider which corner of your box is closest to the viewer. (Should be the center of the Y-Shape you use to draw the box). The edges going AWAY from that center converge. For the top left box on page two the two orange lines converge towards the top, The center of the Y share represents the opt corner of the box so the lines should converge towards the botto, not the top. (I hope this explanation makes sense)

3) The second problem is probably caused by this one. Most of your problems seem to be with the invisible part of the box. When you draw through your boxes, the "hidden corner" is placed in a way that makes your lines onverge in weird ways. Taking the top left box on page two as an example again, you placed the hidden corner (the one that would normally not be seen) in a position, that your blue and green lines converge in the right direction, but you placed it too far to the right for the orange lines to converge as well. When you decide where to place your "Hidden Corner" think about all of your axis. The position of this corner will affect the convergence of your orange, green and blue lines. before you place it, think if all of your lines would still converge correctly. put a dot where you think it should be, and then ghost lines for your hidden edges without actually putting them down yet. If you see that one set of lines might not converge correctly, you know that you have to reposition your "hidden corner".

4) Sometimes the visible parts of your box are a bit off as well. On your last page, the two boxes on the right side look a bit funny. This is because some of your edges converge too fast compared to the other edges. The box in the middle on the right side for example has two sets of edges that are alost parallel which means they hardly converge at all (Green and red). The blue lines however hit the vanishing point a few centimeters awa from the box. While it is not impossible for one set of edges to be almost parallel, I believe it is impossible for tow sets of edges to be almost parallel (correct me if I am wrong on this people). I mean of course all edges are supposed to be parallel in perspektive, but I mean your lines are actually parallel on the page. The green set and the red set almost do not converge at all on the that box. That normally only happens if you look straight at one face of a box. But you cannot look straight at two faces at the same time. If you see more than one face, the box is rotated which means, that the lines have to converge. Not sure how understandable this is. It is hard to put into words. Basically where one set of your edges converges, defines how much the other two sets should converge. There is some wiggle room to this depending on your focal length, but that is another topic.

Hope that made some sense for you. Especially no. 4 got confusing I believe… Sorry for that. I believe you will continue to see improvement if you just continue the challenge. It is already visible that you made decent progress on the 4 pages you uploaded.