Man those frogs are seriously stylish. I love them! There's some really cool shapes in those drawings. I'm definitely seconding the keeping your lines light point that Tim brought up. Light lines give you a lot of freedom to make adjustments and experiment with shapes. For example, if you wanted to add even more bulk to the belly on the frog with his arms crossed, you would have an easier time making that adjustment if you kept your lines light. You wouldn't even have to erase; those old lines would just fade out. Using CSI lines, drawing through the contours, and using cross contour lines are other techniques for good drawing hygiene. When you're sketching, you always want to start simple and work towards complexity. Using a good variety of simplified CSI lines will help you determine your proportions, rhythms, and general shapes. Keeping those CSI lines light will give you that freedom to move things around until you find the -best- proportions, rhythms, and shapes. Then, those lines serve as scaffolding for the more complex details that you are saving for after the proportions, rhythms, and shapes are laid out on the page. Drawing through on difficult overlapping areas helps with continuity. I noticed in your rabbit drawing that it's difficult to parse out the anatomy of that front leg (it's a strange pose); it can help to try to figure out the anatomy of that leg behind the head and the back leg, and connect it to the part of the leg that's visible. You would do this very lightly so that you could easily erase if needed or just let it fade away. Cross contours can help add dimension to a quick sketch. You did it in your frog drawing on his back leg. I like using cross contours not just as a way to understand the form, but as interesting visual rhythms throughout the drawing. The course covers cross contours in-depth in the Intuitive Perspective section. I did a sketch from the rabbit reference image below to show how I would apply those points. Hope that helps! :)

I really like the simplification of form. Some super cool choices there. The straight in the dog's brow is fun. Can you focus on line quality for a while? I'm seeing some "hairy" spots. Maybe some of the areas where you're searching can be a bit lighter? Then only adding the weight once you've found the placement... I'm not particularly experienced. Only piping in to share observations. It can get frustrating to not get feedback when you're looking for it. Overall, I dig it and I hope to get as good at simplification as what you've demonstrated here. Hope that helps!