Minty Chip

Your vision Is great, however what is bothersome is the lack of background here, the horses anatomy could really use improvement also. You should look into stock photos for anatomy practice.( animals are very hard to master I am aware ) If yo want this to REALLY sing you could instead of a black background use a color such as light blue with a background of brightly colored treats like the Ice cream cone on the right side. Further more, your name/OC title should become smaller and be at the bottom at the picture so it does not interfear with the art. You should practice with colors and animal anatomy really from what I see here.
(hope I was helpful!)
~Benjamin Biddix.