started working on a low poly sephiroth model. I think the body turned out quite good. But now for the head. Anyone who could give me some tips on how to make a low poly head without any reference at all. I have searched around for tutorials, but there are no step to step tutorials. That shows a technique without using reference. So anyone who can help 
That’s because using a reference is the place to be at–it’s faster and more efficient, and the only real alternative is knowing enough about human anatomy and proportion to be able to eyeball it yourself.
This is pretty decent as far as references go–I’m assuming you’re in for the old-timey styled Sephiroth–and you could probably safely eyeball the side view; you could also use the side view of another anime-styled picture to give you an idea of how to make your form.