I found a watercolor tutorial on YouTube that helped me think more about doing studies of individual animal parts instead of jumping in with painting the entire animal. Rebecca Rhodes has a few demos (this one is How to Paint a Realistic Dog Nose in Watercolor) as well as longer, full tutorials in her online school.
It was helpful to see her process of abstracting the shapes of the nose and building the tones up by glazing. She gives really detailed and thorough instruction, which is nice for learning how to paint realistically like this.
I’d like to do more studies of individual animal details. I also bought Pat Weaver’s Pet Portraits class on Craftsy and cannot wait to dig into her looser style of painting animals! This class also includes some demos on painting dog and cat eyes before doing the whole head.