Ok, let me see how I can put this in words…
The head model looks great for the fact it’s only your second attempt, but there are two vital things that are happening with it at the moment, which I feel if altered, could make a huge difference.
Firstly, and something you’ve already mentioned, is the seam all the way down the middle of the face. I’m assuming you’ve mirrored your geometry, and this is what causes seams, when used with something like the mesh smooth modifier (max). The way to get arround this is to either add some extra geometry close to where the seam is, thus making the difference between verticies negligable, and so hopefully reducing the seam, or you can try reducing the weight these verticies have on the smoothing (but I’m not exactly sure how you’d do this), or you can do what I normally do… which isn’t ideal, but does give fast results, and that’s to move the verticies (in this case inwards) until you remove the seam.
The second, and possibly the biggest, is something that all ‘noobies’ (not that I’m not one, lol) will do at first… and with a little more work, I think this model can break out of it. When starting with a cube (which I think you’ve started with for this model), a modeller (especially one who’s new to a particular practice… e.g. facial modeling) will tend to move the verticies in the front and side view to make a head shape, but forget the top view… I bet if you look in the top view it will still look vaguely rectangular… the front edge (just next to the outside of the eye) is very much a straight edge… whereas a real head is more spherical.
A technique I use for getting rid of such problems is to work on a vertex by vertex manner. I select a vertex that looks wrong, and I look to see where it is in the front viewport (relevant to my reference image/plane), it may be that it’s on the outside edge of the eye for example, I then go to the side viewport and move the vertex back until it is where I would expect to find the outside edge of the eye. You repeat this process (look where it is in on viewport, and move it to match in the other), and hopefully, if you have good reference planes, you should begin to eliminate the problem of having a ‘cube’ looking head.
Another solution, but one that I personally don’t like, is to start with a sphere instead of a cube, but I feel this gives you too much geometry too early on to really get the model working well.
I know there’s a lot of information here, but I hope you can pick up some things from it, and improve this, and other models. I’m far from an expert… I’m relatively inexperienced at organic modelling, but these tips/comments are things I’ve picked up from others on my way to learning (either by asking questions… or recieving crits. from others).