This tutorial will give you an overview of how to build a subdivision surface model using 3D Studio Max. This is not a step by step tutorial, so you'll need to have basic knowledge of how to use Max.
I prefer to create the lowest poly model possible for the job, then use turbosmooth to subdivide it. The reason I do this, is to avoid the massive slowdowns from trying to rig a high polygon model. Previously, I created a see through model of a human, where all the muscles were visible. The model was so complex that it slowed my PC to a crawl. Animating it was almost impossible. Even with a low poly model, you will experience slowdowns, once you add morph targets, rigging, hair, and multiple characters in a scene.
You must first start with a phot reference of a design drawing of your character. You will want to add it as a background image to the front viewport. Remember to lock it to the viewport, so that the backgrounds moves with your model.
Before I continue, keep in mind that I am only building half a model. This can easily be mirrored to create the opposite half.
Since the nose is the most complicated shape on the face, I'm going to start with that. Create a 2D rectangular shape and convert it to an editable poly (not editable mesh). Since subdivision surfaces work best when your model is made up of quads, be careful to avoid building triangular polygons. When you have a triangle in your polygon model, one of the corners will appear pinched. It's the same as taking two corners and placing them in the same place. In addition, you should try and keep your quads as regular as possible, especially on smooth flat surfaces. If you must use a triangle (sometimes you will run into this situation), then try to place it in an area where it won't be as obvious, like the corner of the mouth, or a tight corner around skin folds.
To build more quads, select an edge, and hold the shift key while moving it. This will extrude that edge and create a new quad. Move the vertex to match the shape of the nostril and repeat this process until you end up with a rough shape that fits the contour.
Now, switch to the scale tool. Select the perimeter edges of the nostril shape, then hold the shift key down, while increasing the scale. You should see the edges extrude into new quads around the nostril shape. Don't worry about the depth of the vertices for now, just move the vertices in the X,Y directions. We'll worry about the Z direction after we build the basic shapes.
To give the nostril some depth, select the inner polygons that make up the nostril and click on the extrude button. Click and drag until the polys extrude inward. You should now end up with a 3D shape.
You can check to see if your subdivision surface is working by checking the Use Nurms Box, and increasing the iterations. If everything looks smooth, you can continue working. Uncheck the box, so the model is not subdivided. Don't forget to inspect the smoothness periodically to see where you need to add more polys or if your surface is not subdividing correctly. FYI, this checkbox does the same thing as turbosmooth, but you must never use it for rigging. Always keep it unchecked before rigging, otherwise your skin weights will be destroyed whenever you render your model. Always add turbosmooth after you finsihed rigging the model.
Here's the harsh reality of modeling. Most of the time is spent pushing and pulling vertices, and edges. I only use a handful of buttons in the poly modifier. Most of my time is spent moving points around to fit the character design.
OK, now we fast forward a little. The parts for the face are done. All I did was extrude edges to create new polys, and move the vertices to match the reference image. As you can see, the nose mouth and eyes are done. Don't worry about making it perfect, you will be making more adjustments later. Now it's time to move the vertices in the Z direction, so set up your side view and start moving the vertices. Keep the objects separate, it's easier to work on smaller objects when moving vertices around. When you are done with the individual parts, you can stitch them together by using the create button. Simply build polygons using existing vertices.
Instead of describing each step in detail, I'll show the progression as a series of screen shots.