Redline for you lovely! <3
For tips, use references honestly, you can't figure out the details better than looking at the real thing <3
You have a great sense of proportion and that's really awesome, what would make your art more alive and realistic or to a style you want to develop, shaping out the limbs around muscles and bones making definition will do wonders. Imagine the bones on a skeletal horse, now wrap muscles around it. Then stuff the whole thing into a big clay piece and slowly cut away the clay until you have a thin layer of clay over the muscles and bones, metaphorically speaking. At least that's how my mind works around anatomy cx <3
But anyways the head looks good, though I'd suggest making the muzzle a bit more rounded like a zorse's and soft, curved lines to give it a nice look. Attaching the ears a bit further down would be awesome too, though the way you drew them looks gorgeous!