Reddit reviews Animals in Motion (Dover Anatomy for Artists)

You need to learn anatomy. Get books on artistic anatomy.

An Atlas of Animal Anatomy for Artists (Dover Anatomy for Artists)

The Art of Animal Anatomy: All life is here, dissected and depicted

Animal Anatomy for Artists: The Elements of Form

Start simple and learn the different techniques you'll need. Then build your knowledge by combining things as you learn.

I'll just take time and practice. Lots and lots of practice.

If you plan on animating them, then you will need ...

Muybridge's: Animals in Motion (Dover Anatomy for Artists)

and watch videos of them.

This pretty much sums it up: The Road to Learn Blender