Well...
It looks a lot like a cartoonish look, is that your aim?
If so, then you don't have to change a whole lot.
But if you want a bit more realism, take a look at an actual Red Fox.
I'm using my insanely powerful psionic powers to manipulate your mind into telling me that you have a Fox fur, right?
soooo
http://www.wildernessclassroom.com/www/schoolhouse/boreal_library/animals/photos/red_fox_kit.jpg
http://www.stefanounterthiner.com/images/Grandi/Red%20Fox%20013%20POSTER.jpg
Time for IRL pics

.
But because I am not a fox person (havent' drawn one) all the advice I can give is to look at the fox's anatomy, skeleton, muscles, and skin/fur. Then, after you figure out the animal, start working on human anatomy. Then in your mind combine the two and viola!
Ps,
Yes, it does take a while but it is worth it
pps
You might also want to take word of another fox drawer, I am a draconic person ^.=.^; .