If I was commissioning a fursuit, I'd like to have a good reference sheet, same as I'd use for commissioning an art piece. At least two views (front and back), maybe a side view and detail shots if needed. I think most builders need a reference sheet to make you one, I haven't run into anyone yet who does fursuits just based off of a text reference/description.
If I was making my own fursuit, I'd just have some sort of rough sketch down, throw some quick color on it, and then see how that works. I somehow get the feeling that if I was making a head I'd just take a look at what fur colors I had available and do the actual patterning on the head base itself based on how I was feeling at that particular moment
