Hi, honestly this is a pretty good submission and I congratulate you upon that but hopefully this critique will help you in some way.

Starting with your arrows I can see that you are trying to keep them consistently widening as they approach the viewer, and your doing a great job but accuracy will come with mileage so keep practicing. The most important thing to point out here though it's the use of lineweight, just remember that you want to keep your applications subtle and you'll become consistent with mileage, here's a little demo that can help you with that.

Moving to the organic forms with contours, your doing pretty well keeping the shape of the sausages consistent, but don't push yourself to use many contour lines/curves, the more you draw the more likely you are going to mess up and undermine the drawing. A few well placed contours can do a better job.

You are doing a great job when it comes to the textures analysis, you're clearly focusing on cast shadows rather than outlines, I also want you to look at this demo showing how to work with thin line like textures.

Your work in the form intersections clearly shows that you great the concepts behind it.Your forms are looking quite solid here and they believably appear to belong in the same cohesive 3D space, good work.

Finally the organic intersections, you're keeping your forms simple and easy to work with which is a good strategy to help produce good results.