Whitetail Deer - From Skeleton to Fur

I’m trying to create a fully rigged, groomed, and realistic deer model. So far, I’ve modeled the skeletal system and downloaded the X-Muscle system add-on but have yet to play around with it. I’m having a hard time finding anything decent online about creating quadrupeds but, I’ve seen some really great models similar to what I’m trying to accomplish including the ones that come with the X-Muscle add-on. I was hoping I could find some guidance on here while I work on this.

So, first question, should I start working on the muscles next, rig the skeleton first, or do something else? I know the basics of rigging but haven’t quite figured out what a good rig should look like or all the tricks to rigging.