first of all, you just need to keep doing it, the first head you make will probably suck, just like the rest of us.
don't believe me?
just look at the picture.
Second i want to say is that you work with to much poly's to start with, it's hard to tweak your model when the polycount get's higher.
i normally stay around 300/400 faces when roughing out the shape.
and last if you are trying to make a certain individual(selfportret perhaps?), it is best to first find as many pictures from different angles about them that you can get, so you can match your model with the pictures under certain angles and look what's off and what you got right.

Keep working on it and you will see it will get better