I see some areas where you can improve.

• The first is the organic forms with countour curves some of them seem flat but not all of them, but keep that in mind.

• You can work on making the transition from dense to sparse more subtle in the texture analysis, in my opinion it is quite dramatic in your exercise.

• Your organic dissections are good, but remember that at the edges of the sausages the amount of detail would increase, because they wrap around more dramatically at the edges

• The form intersections is a a complicated exercise, so the only thing that i can recommend you is to remember how two planes intersect, even if they are circles ( a cylinder top/bottom or a cone base) they are going to intersect as if they were squares. But above all just keep thinking in 3D.

• And you can improve in the last exercise by making the cast shadows larger and wrap them around on the form they are being cast on

And that's it, sorry if it is not clear enough as English is not my native language