Nice work here! You're closer with your proportions than you might think, these are pretty good for loose sketching from observation! Don't worry about the anatomy right now, keen observation will get you most of the way and you're picking up a lot of great cues from the reference. For now focus more on observing correct proportions while in the earlier stages of sketching light and loose. While you're sketching, it helps to flip the entire canvas to check your proportions. It'll immediately show you where you're off. The proportions of the thumb and index finger are a bit large compared to the rest of the fingers on Spidey-hand, but you maintained a good deal of the gesture for the entire arm. You might be zooming in on your work during the sketching process, which can lead to tunnel vision and losing control of the proportions so try to stay zoomed out where you can see your whole sketch. It looks like you're still a little hatchy with your lines, it takes a while to get used to using long flowing CSI lines. Try to get your whole arm and shoulder working instead of just the wrist. Tougher on a tablet surface, but try to remind yourself to work confidently from the shoulder when executing these longer continuous lines through the forms. Hope this helps, definitely move on and check out the demo and critiques for this on before you try again, you'll pick up a lot of great tips. Keep up the good work!

You will develop this skill with practice, absolutely! It will take some experimentation to find the sweet spot. You want to work at a brisk pace but not so quickly that you stumble over your decision making. My advice is to try to find ways to simplify a bit more, using CSI. Focus on the biggest forms first; this will help you figure out your general proportions, and as you work you can figure out the smaller forms.

Your hand drawing has good flow! It feels really clean, which is great, although this assignment gives you more permission to be a bit more exploratory with your lines. I would encourage you to loosen up a bit for your next drawing; don't be afraid to overshoot your lines. It can be difficult to -not- overshoot when you're going for energetic, tapered strokes, so I think you have room to push that energy a bit more. It's a learning curve for sure if you feel better with controlled and careful linework, but it's great for learning how to use your elbow/shoulder to draw (drawing larger definitely helps here).

Nice work overall! I like that you still thought about CSI lines for this assignment, as that's a principle that's helpful in drawing overall. Keep focusing on gaining a flow in your drawing as you sketch -- the goal is to get a loose, confident line as you put pencil to paper. I like that you redid lines until you found the correct mark, as being able to put down a mark and correct as you go is an important part of the loose sketching process. I would recommend to finish the line fully, even if you feel like it's wrong, in order to build a momentum instead of starting and stopping too quickly. You can still redo it, but following through helps keep your hand in a drawing flow. If it's looking too messy with all the overlapping lines, try starting lighter with faint lines, then once you find the correct line, go over it with a darker, final line. Hope this helps, you got this! :)