Good job on these, @nahgul! I agree with @Crystal Blue (she/her) - for this specific exercise, try as much as possible to visually describre the 3D forms, either with planes or with cross-contours. This applies to the rabbit's head and also to its ears, as well as the dog's ears and tail. Other than that, keep it up! Hope this helps.

the legs and feet on the otter look really solid! The rabbit head looks fine, but because you’re practicing structure you could probably define what 3-D shapes it’s made of more clearly