So just to summarize upfront, your organic forms with contour lines have some pretty significant problems, but your insect constructions are largely quite well done, with one major issue that just comes down to approach rather than skill, so it should be fairly easily sorted.

So starting with the organic forms with contour lines, the big problem here is that the sausage shapes themselves have been drawn very hesitantly, resulting in all kinds of wobbles. Those lines are not remotely smooth, in a way that suggests that you're either drawing them very slowly, or from your wrist - or perhaps both. There's not much to be said about that, aside from you needing to employ the ghosting method, and to draw from your shoulder. You don't need to draw them super quickly or anything, but it is important that you execute the marks with confidence, avoiding steering your pen with your eyes as you draw.

On the bright side, it's clear that you did draw them hesitantly in order to stick pretty close to the characteristics of simple sausages. It shows that you understand what you should be aiming for, but in truth, the wavy, uneven lines of the sausage shapes contribute their own kind of subtle complexity, which makes the forms feel less three dimensional.

Same thing goes for the contour lines - they're being drawn pretty hesitantly, and need to employ the ghosting method to maintain confidence.

Moving onto your insect constructions, as a whole you are actually doing a pretty good job. You're building these complex objects up through the combination of simple, solid forms, which helps maintain the illusion that the object overall is still three dimensional.

The key issue at hand here though is that you are way too liberal with your use of line weight. Line weight is a tool with a very specific purpose, and you should not be applying it to everything in the way that you do. Right now it seems very much like you're tracing back over all the lines you want to keep, or purposely drawing them darker, while leaving the underlying construction light and faint - this is incorrect.

Line weight should be reserved only for specific localized areas (meaning, not to replace the entire length of a given line, or reinforce the entire silhouette of a form) to clarify specific overlaps between forms. It is to be kept subtle and light, whispering to the viewer's subconscious to help them make sense of what they're looking at.

Long story short, don't trace back over your constructions as you've done here. Focus on drawing every mark confidently, and on constructing new solid forms to attach to your construction to continue building up to greater levels of complexity.

Another reason this is particularly important, is that once you've established a solid, 3D form, redrawing or adjusting its silhouette (which can often happen by accident when you try to trace back over it) will actually undermine its believability, breaking the connection between the 2D shape on the page, and the form it represents. It's critical to keep all your marks smooth and confident - as mentioned in regards to your organic forms with contour lines - and not to stiffen them up by tracing back over them. Tracing itself is a problem, because it tends to make students focus too much on how the line they're following sits on the flat page, rather than how it represents an edge in 3D space.

Looking at how you've been handling your leg constructions, for the most part you've adhered pretty well to the sausage method - though there are some cases where you drifted away from it, either intentionally (because you felt the sausages didn't quite capture the shape you were after), or unintentionally (in cases where you didn't stick to simple sausage forms). The key to keep in mind here is that the sausage method is not about capturing the legs precisely as they are - it is about laying in a base structure or armature that captures both the solidity and the gestural flow of a limb in equal measure, where the majority of other techniques lean too far to one side, either looking solid and stiff or gestural but flat. Once in place, we can then build on top of this base structure with more additional forms as shown here, here, this ant leg, and even here in the context of a dog's leg (because this technique is still to be used throughout the next lesson as well). Just make sure you start out with the sausages, precisely as the steps are laid out in that diagram - don't throw the technique out just because it doesn't immediately look like what you're trying to construct.

The last thing I wanted to call out is just in relation to details/texture. While there obviously are patterns and local colours (like where the colour of a given surface changes) that we may feel inclined to capture - because of the limited tools we have at our disposal (pens that only allow for solid black or solid white), we simply don't have the means to capture all that additional information. As such, try to ignore patterns/colours and focus only on using filled areas of solid black to capture specific cast shadows.

What we're doing in this course can be broken into two distinct sections - construction and texture - and they both focus on the same concept. With construction we're communicating to the viewer what they need to know to understand how they might manipulate this object with their hands, were it in front of them. With texture, we're communicating to the viewer what they need to know to understand what it'd feel like to run their fingers over the object's various surfaces. Both of these focus on communicating three dimensional information. Both sections have specific jobs to accomplish, and none of it has to do with making the drawing look nice. So as a whole, the approach lines up well to focusing on employing cast shadows to capture what the viewer might touch with their hands, rather than what they might see with their eyes.

Now while your work is overall coming along well, I do want to sort out those organic forms with contour lines, and also make sure that you understand what I said about line weight. So you'll find some revisions assigned below.