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!
On our server we have too many people building around green but the best spot I have found is west of red tower to the river with three water falls, just go up to the second and I've never left empty handed, I personally own 17 and I'm working on my 4th generation of mutations!