The storyline of Flax is an important part of creating a good concept for a story. Although little was known about her or the story beforehand, the concepts helped to develop said story and took it into directions nobody thought of before.
Concept art has many facets. One of the most important ones is storytelling. Your concept could just be of a generic creature someone could get across, but won’t think more of. Or a leading one, like Flax, a prominent mount in the storyline. Both types have a clear overlap in how you should approach them. Habitat should be taken into account as well as functional anatomy based on their habitat and behavior. But there is way more to a character or creature that has a prominent place in a story. And Flax, a Lutherial Vixen is a good example of that.
Rendering the final pick of all the concepts you sent in earlier is much the same as any drawing. There are however some things you might need to keep in mind, depending on your client and the project you’re working on. You might wonder why rendering is even part of concept art to begin with, because concept art is everything but rendering the artwork. Allow me to explain.