Scenes rendered in this way are really difficult when you're working with areas of color and light that are a little bit too close and similar. Being able to compose a scene "meant" for color is the key, and that means that it needs to have its key defining areas represented with lots of either contrasting tonality, or contrasting color.
What made this image a difficult one for you was not really that you "muddied" it up... I mean,...you used the colors that you felt were right for it,..and they are,...you chose well. The problem was that the contrast for those colors, in areas that "needed" to stand out from one another, were too low (low in contrast), such as her lighter-cream-colored chest-fur and the similarly-colored <ahem> "body-fluids"...
As a result,...several areas of the image seem to "run-together" a bit much... But....look at what does work,....the eyes,....why? Good contrast! They stand out on their own...
It's still a well-done piece, though... It's not a failure at all,..merely a lesson learned...
Half the lesson is having the cajones to work with natural media to begin with! It's a brave and bold thing to do this, it's never easy,..but natural media can be really rewarding to master...
Fun stuff, my friend...(despite my somewhat prudish embarrasment,..which I really can't afford to have when visiting here
)..
Keep up the great work,...and learn from your victories with it as well as those pieces you perceive as "less than victories"....
Jadúgara ^_^