I think your arrows are good, but some of the ones of the first page are a little thin. Try to draw the nearest side bigger. But they show flow, nice!

Now, remember to use cast shadows, not form shadows. In the first two is more or less noticeable that you used form shadows. Crumpled paper isn't easy, so try to identy first the shadows that are casted in the rest of the surface. Then, the ones that are shadows because is an arising surface that due that blocks light and is reflected on itself. Just keep that in mind

In some dissections you used cast shadow very well, and in some you use form shadows. So, keep in mind to use cast shadows most of the time.

And also some textures in the dissections flattened the sausage. Recall to wrap it around.

Form intersections are tricky, so I recommend to do the following: mostly follow the surface of the form that is being intersected, but don't forget about the other form too. Follow both, but one more than the other.

I noticed that some of your spheres aren't remarked two times, which is something you should always do. And I'd recommend to ghost them more.

Your organic intersections looks fine, but remember to stick to simple sausages. That means, no bulky things at the end. Is a ball+tube+ball, with consistent width. Keep that in mind always

And also, don't add too many contour lines. Three or four will suffice if they follow the surface properly.

-Just my opinion in general, but good job!