Most of your pics are taken from a bad perspective, you might want to pick up a paper scanner to help with that. Your superimposed are decent, they'll simply need more practice to tighten them. Your ghosted lines all seem to overshot the mark. Try letting off the pen early, that could end up helping you. The ghosted planes are all very samey, you should be more experimental with the dot placement. You also need to work on your line accuracy. Your ellipse tables have the same problem. Make the line in the middle of the table more freely curving or jagged. You also need to vary up your minor axises. You ellipses on planes need more varied plane shapes. Once again, your funnels lack variation, please try to be more experimental with your minor axises. I can't see anything wrong with your plotted perspective. Your rough perspective is missing an entire step, you need to add the depth lines. These show the accuracy of your lines going to the VP and without them it's very hard to grade your skill. Some of your rotated boxes, like the ones on the edges, are not rotated enough. Your organic perspective is pretty bad. You need more boxes, in more sizes. For actually making the boxes look like boxes, try to spend more time ghosted your lines meeting at the VP.