I made a drawing for you to understand what you need to improve. So first of all, a horse is not made of a bunch of lines, filled with random colors. In any place you will be, there will be a source of light. So, according to the spot of the light you need to give your horse spots of shade - reflect - and neutral colors. And you need to add more details ! Look at a horse's picture, you'll see all the muscles, tendons,and all sorts of things, that also create shade, etc .. To help you a little here's my little drawing ! If you need more help → Pm ! I only did it for one horse, apply it to all your coats, they'll be lovely ! (even though they're all already the cutest ever !! ♥)