Great looking character and the topoplogy looks good to me for the most part. I can see the tris appearing around the ears but I am not at my workstation till tomorrow but will take a look then to see if I can sugest anything to get them to quads.
One possible way to get the polycount down might be to get rid of the hair you have modelled and instead create a couple of poly planes with the hair attached as an alpha map.

Great work so far though, you intending to rig and texure him as well.