The problems you mentioned aside, I think you've done a good job. You're building up each insect/arachnid with simple forms first then building on top of it which is the main point of this lesson. You also make good use of the line running down the middle of the head, thorax and abdomen. One thing I'd like to bring up is that you sometimes leave forms open, like on the 5th image - https://i.imgur.com/NzoLKsC.jpeg. Adding extra details like the spikes are fine but make sure to close them off and create a proper form (cone-like shapes in this case) otherwise you're undermining the solidity of the overall image.

Tips on wobbly lines that I found helpful:

1. Draw with your shoulder. I'm sure you're aware of this and why its important so I'm stressing this point. If you catch yourself falling back to drawing with your wrist, force yourself to use your shoulder again

2. Make sure your arm movements aren't too slow. The faster you move, the smoother the line will be but the less accurate it becomes, its a trade off. It's physically more difficult to make wobbly lines if you're moving at a decent speed. Try increasing your speed a little (don't go overboard) and practice creating basic forms from earlier exercises with nice smooth lines. Once you're comfortable, gradually slow down while maintaining the smoothness until you can draw controlled, smooth lines

3. Don't try to be perfect. Creating convincing 3d forms is the main goal, drawing smooth lines are much more helpful in conveying this than trying to have perfect accuracy and ending up with wobbly lines. Accept that your drawings will not be 100% accurate and thats okay

On lineweight:

Adding lineweight is difficult and I think it comes down to accuracy which will improve over time with practice. Make sure to keep applying the ghosting method and draw a single, confident line.

On proportions:

I think proportions come down to

• observation (noticing proportions accurately)

• drawing accuracy (drawing the proportion you're intending)

Proportions isn't a huge focus in this course so I wouldn't worry about it too much other than paying close attention to the relative proportions of your reference image and trying to recreate it (again don't try to be perfect)

Still, its an important skill to have. If you want some some focused practice, try drawing from still life while applying measuring techniques (measure using your pen with your arm extended) go look up some tutorials for this. It will get you to pay attention to the forms your and their relative size and position by measuring them and then translating that to your drawing.