For you to draw something well you have to understand what you are drawing.
If you want to give it volume, depth or even texture you have to know the proportions and the anatomy of what you are drawing.
Many people struggle to draw animals, especially mammals (the most popular ones) because they simply lack the essential information to do it. Mammals, for instance, have all the same bone and muscle structure, so if you know how to draw humans you can relate it to the other mammals. What would you think if I told you that dogs have feet? Or that horses have toes? Or even that elephants have elbows? Yes they do, and so do mice, bats and bears. The biggest difference from one to the other is going to be the size and length of their bones. I know that the dog's upper-arm is shorter than the human's in relation to their body, as their fore-arm is longer. Now, if I know where its elbows sits I will know where its arm will bend. Therefore if you know where the animal's limbs are and their variations in relation to the human's limbs you can even make them do what humans do, the way they do. You can draw mice cooking in the kitchen, dogs sunbathing at the beach, and bears having tea. This is called Anthropomorphism.
Anthropomorphism is the attribution of human characteristics or behaviour to animals or objects, and it's very popular in storytelling and art. Most cultures have traditional fables with anthropomorphised animals and until today we can be very fond of children's books' humanised characters like the classic Beatrix Potter's Peter Rabbit. Miss Potter was the author and illustrator of Peter's story amongst many others, and you can see from her tales that from the beginning she was a very good observer. She grew up surrounded by animals, filling her sketchbooks with their movements, with how they stood, walked, swam or flew. She was so observant and good with drawings that her study and watercolours of fungi led to her being widely respected in the field of mycology (the branch of biology concerned with the study of fungi). After successfully publishing The Tale of Peter Rabbit in 1902, she began writing and illustrating children's books full-time.
We are so fond of Peter because we know he is like a boy being a rabbit in a blue jacket. But Peter can also be a rabbit being a rabbit; when he decides to eat from the garden of the complete human old Mr. McGregor. You can notice the next time you read it, that Peter loses his jacket (the main thing that reminds us of his human boy side) right before he meets old Mr. McGregor. And for the whole scene with him, Peter no longer walks on his two hind legs, speaks, or acts like a humanised character in any way shape or form. He runs and hops, knocks things over and hides as a complete bunny rabbit. He will only recover a bit of his human side when his mother punishes him for losing his jacket and sends him to bed without supper.
This is something subtle that happens in stories that needs no explanation and that nobody ever said it was a rule. But Beatrix knew - as CHILDREN KNOW - that a reality break would happen if Mr. McGregor saw Peter as an anthropomorphised animal. Because in HIS reality it wouldn't make sense. That's the magic of children's make-believe rules. And we just know.
Anyway, there are a lot more fantastic things to talk about story making and the children's world but the point is that Beatrix knew her animals so well that she could draw them as they were as well as being human like. So my advice for today is to know your characters, know your objects, know your structures.
Drawing is like talking about a subject: if you understand it well you can explain it well.