Have a look into the proportions of the human head, where everything is in relation to other parts.
Also have a look at the topology thread both on there (in the WIP section) and over on CGtalk in the maya section as that will help you out on your layout as it looks very concentrated in some parts that with a tweek can help you get a better defined face with lower polys, then you can add loops to define areas.
"No pressure, no diamonds" Thomas Carlyle