Just like special effects in film...you should not notice it...
Post work/painting should just make your art look better! :)
Details below image what I did in post
In Poser 2014, I used subdivision- set very
high on bridle (3) and 2 on saddle, 1 or 2 on horse. Already this puts you ahead
on needed post work of the wonderful reins for one thing! The post work I
brush hair over hooves, blur OUTLINE of figure in prep to have it blend in better with a background, inverse selection and unsharp mask on whole figure. BUT when I sharpen, I selectively blur the outline of things like saddle straps so they do not stand out from the horse's coat with a really light outline, that made the horse's coat look "higher" than the strap.
For this horse, with the dark leather saddle, I actually used curves to lighten the whole image just a TINY bit, so that it brought out the details. (this horse is standing in "firelight" lighting) I then did a small amount of CONTRAST to bring the colors/shapes up. Sometimes I will add a bit of saturation but didn't have to here. I worked with lighting on the lower teeth, because the light had hit them oddly. I added subtle dark lines around ears, darkened the nostril HOLE too.
I wanted a 'roached mane' so did that with cutting/copying the TOP of the mane to keep the natural looking ends, duplicated it, and brought it down to shorten the mane... I used the warp tool to make it really "fit". I also did some small bits of post work on the neck where my modified mane met body. The forelock had a crimp in it, so I copied just one section JUST ABOVE the crimp, lowered it, and brushed it into the rest of the forelock...