Agreed ^^^^^ I have also (very recently) discovered that dark shadows are necessary to give that drawing a 3 dimentional look. For instance, there are almost always very dark and sharp shadows under the straps of the bridle or halter that I used to not even attempt to draw at the risk of making the shadows stick out like a sore thumb, but I learned that such shadows do make the drawing as a whole "pop". But in the meantime, I agree to go back and find areas that just happen to be "darker" and blend them with the side of your pencil. As with anything, practice makes perfect. I have had to create a lot of flops in order to advance my art skills. I definitely think you are on the right path and ready to challenge yourself. Can't wait to see more drawings from you.