You could try to draw with ink pen, that way you can't erase your mistakes. I believe it better to embrace your mistakes since that's how you get better :)

Hi @Jean-Nicolas Bouchard, I can tell that you've been thinking about form when doing these. There are some lines in your drawings that suggest threedimensionality, such as the crosscontours in the owl's brow, or the overlaps and crosscontours on the cameleon. - I think you need to do some where you make the boxes and geometric forms really clear. I mentioned that some of the lines you put down suggested form, but I also sense that some of them are curving the wrong way. You don't want form to be ambigous. Building the creatures with clear geometric forms help with that. I think clarity is key for you to improve. It will reveal what you don't know, and strengthen your successes. As a mantra for this exercise,you could have: Rather clear and bad construction, than good but ambigous. This might require spending more time on each drawing. Analyzing form is not an easy thing. It might help to start with a very light underdrawing, that focuses on gesture and the major shapes and round forms. Then on top of that you can commit to boxes and clear geometry. Or you could start with gestural lines, then stack forms on top of it. The joints might be complex so you could leave those out in the beginning. And remember, you can construct in whatever way you want. You can construct a single animal in a variety of ways. There are constructions more efficient than others, but for this exercise I would be in and exploration mindset. As a last note, remember that this in an exercise to practice certain concepts. In your other drawings, you might want to use more organic forms.

More neck! :)

Just getting started in my art journey, so I don't have any critique to give but I just wanted to say that these are wonderful

If you're struggling with the overall perspective you could try starting your draw with a simple 3D cube to set the boundaries of the animal and setting the mail vanishing points. Check for Kim Jung Gi box drawings

It seriously looks awesome. Despite being all 3D and blocky, your animals feel alive and full of gesture. Really good balance there.

I would probably simplify the owl into just a cylinder for the body and a cube for the head.

im still learning but I can say for the man's pec muscle could be less flat to his chest maybe just a bit puffing out and maybe even half of his pec showing (side angle) and it looks like his right leg is facing more right then his hip if that makes but so far that is rather amazing!!! i hope this helps!

I don't think you simplified too much. The deer looks great and I'd say whatever mindset you had while drawing that one is probably your best bet to understanding how to manipulate structure. I do suggest to try to tier your lines though. Keep your cross contours lighter and your contour lines thicker. Any important lines like gestural lines (even if their "arbitrary") or cross contour could stay thick as well. Kind of like your deer drawing. This just helps with readability for both you and others.