These are pretty good! I think you should focus more on starting with the basic geometric shapes of the animals and then adding the flesh and fur details. That will help with creating structure and a more solid 3D feel. The sketches where you did that have more weight than the ones where you went straight to outlining the animal. Starting with geometric shapes will also help with perspective. It's easier to understand the perspective of a box/sphere/etc. first, and adding animal details from there will make the perspective come to life!
I really like your work! Maybe next time try drawing out your basic shapes on one layer with a different color and turn down the opacity then draw the final on a different layer. When you use traditional you can lay out all the shapes lightly and then draw over them hiding them while when your using digital all of the lines are solid and bold making it hard to read. So either try using a different brush or lighter color and then do the final sketch on a seperate layer. This will make it much easier to read and it will help perspective because your starting shapes wont muffle together with the depth of your actual drawing.
Hi! Your perspectives and proportions seem fairly good. You can definately tell what each animal is. Might I suggest just brushing up on some animal anatomy? Specifically for digitigrades (animals that walk on their toes and appear to have "backwards knees" like dogs). Learning some basics of different types of animal limbs goes a long way. Great stuff!