If your used to Nurbs-modeling it's a bit hard to model a poly Head.
A good tip is, to take a cool looking head, and make it a template. The head we're going to model, was one of my first modelled with nurbs. I modelled it from a side and front sketch. Another cool was is, to took two pictures of an woman-head, print it out (it's good to lighten the picture before you print it) and paint some guide lines. If you model a poly-head it's almost the same way.
If you make a layer for your template, you can toggle it on and out when you need it. It's also sometimes a good idea to make this with an imageplane.
For the poly-head I began with an poly-cube. Move it 0.5 unit on your X-axis. The best way you do that is to enter it in your cannel box. Than you should delete the inner poly-face. Than it's no problem to mirror it.
You can also use this little script to make a poly wit no shading and no inner face...
polyCube -w 1 -h 1 -d 1 -sx 1 -sy 1 -sz 1 -ax 0 1 0 -tx 1 -ch 1;
setAttr "pCube1.translateX" .5;
select -r pCube1.f ;
move 0 0 0 pCube1.scalePivot pCube1.rotatePivot ;
setAttr "pCubeShape1.overrideEnabled" 1;
setAttr "pCubeShape1.overrideShading" 0;
One of the best scripts I've found is the "Connect Poly Script". It can make a smoothed version of your rough model, disables the shading and makes a mirror-copy. You than have an instance and every time you change something in your rough model you can see the result in your "end version". It has a good interface with buttons and so on. It's a good way to learn how the "Split Poly Tool" works. You can get the script on www.highend3d.com in the Maya/Script/Modelling section.
It's also a good idea to use your shelf and marking menu for a custom poly-setup. You'll always need things like "Split Polygon", "Extrude Face" , "Merge Edge/Vertex" and so on for your model...
The second stage is to get a basic shape. You have to find the major guidelines for your model. Than you begin to refine your shape with "Split Polygon Tool". It's almost the same as with Isoparms, you should always just refine a few edges and than move the new vertex to their position. The second stage ends, with a basic head without face. It's also a good idea to save some of your basic shapes. When you need an other head, you can use this basic shape and refine it, so you get for example a man's head or an alien head...
Now you should refine your face. Begin with guide lines around your eyes, nose and mouth. Refine them until you're satisfied with your head...
Some more Tips...
Use the Xray-command to view a transparent surface!
Use the Wireframe on Shaded-command to evaluate the surface!
You can find the script to toggle the command with your keys in my Tutorial / Hotkeys&UI section!
If you have more questions, just use your email editor firstname.lastname@example.org...