When Equus hunting, ALWAYS go to the southern haven. Since there aren't any predators there, you have nothing to worry about. While you're there, it's great for metal runs. And if the Equus there are too low leveled, simply kill them, leave, wait for more to spawn, and hope for a higher level.
Found the Unicorn by Green on the Island. It will be all white and look like a sheep from a distance. In general, they seem to appear in groups of two or more. Move to a safe area or have an escort to clear the area of danger when taming!