topology advice from people who do this for a living http://forums.cgsociety.org/showthread.php?f=25&t=38469
anyhow my last two cents if you use poly to poly modelling to model you will in all likely hood struggle with proportions as you are putting the horse before the cart. You are working on details eyes and nose before the larger proportions are fixed things like distance from hairline to brow, brow to nose, width of the head etc. Its the same if you draw a head and start with the eyes or a nose.
If this is for a still than forget topology there is zero point of fussing with topology. My advice keep the model you have, stop fussing with topology there is no point if you are not animating, switch to proportional vertex model and start fixing the proportions of your model.
proportions you should check,
front facing profile
distance from hairline to brow, brow to tip of nose, tip of nose to bottom of chin. These distances are equal on a standard head but vary according to individuals the should roughly be the same with small variations. From the hairline to the top of the head is half the distance from hairline to brow.
If we use the hairline to brow measure as a standard unit of measure. than from top of the head to bottom of the chain the head is 3 1/2 units in length.
The eyes should fall roughly on the middle of your face. For the width of the face. measuring along the line that runs across the eyes. there is an eye width of length on the outside of the eyes, than an eye width for the eyes and an eye width separates the eyes. so the head is about 5 eye widths in width.
Take the length from tip of the nose to the bottom of the chin, 1/3 down from the tip of the nose is the mid line of the lips, 2/3 down from the tip of the nose is the top of the chin.
the ears should start from the tip of the nose to the brow line.
Fix those proportions, the ones I have given are standard proportions so don’t forget to refer to your reference for you models proportions.
There is no need to tweak or alter your topology for this all you need to do is to tweak vertices about with proportional vertex editing switched on.
Fix the big things first proportions, volume and planes should be more important at this moment more so than topology.
edit - a picture is worth a thousand words all that I have said summarised in a picture
