To see how the big kids do it, I brought a head into zbrush to study.( Poser 5 male)
The polygon count was 10000.
I then realized that the head was basically hollow.
Is there any way we can reduce the polygon count on our heads.
With eyes, etc, I am getting counts a long way from this.
To get low polygon counts, you have to define precisely where all the vertices go; they all need to be doing work in defining the topography of the model. This means moving and positioning the vertices one by one.
You can do this in ZBrush, although it does seem to be a bit antithetical to ZBrush’s modelling methods. Also, because ZBrush does not really allow vertex editing (adding/deleting) it makes it a little more difficult.
A common procedure is to start as low-poly as possible, using the existing vertices to define the basic shape and lay down a nice flow of the mesh. For example, a head can be broken up into planes (the top, forehead, sides/temples, from the cheek to the chin etc.) and you would place the first vertices to define these planes.
Once you’ve done that you can divide to get more vertices and move these to define finer shapes, e.g. the jawline. Divide again to add even finer detail, and so on until you get what you want.
Hope that helps 
PS: ZBrush models are hollow too (just mask one half of a model and ‘Delete points’ to see). In fact, I think all polygon modelling software makes hollow models; all you are really doing is defining surfaces with points.
BC
Many thanks, this answer will have to
be read several times, think I got the
point though, thank you for your time