In previous Part 1 tutorial you have created half polygon face. But, this face doesn't have a depth yet. This next part is the hard one. It takes lots of time and tweaking to get the depth right. Don't worry too much. I have prepared blueprint with modeling guidelines. I think these guidelines will be a lot of help.
Making Basic Head Shape
1. This time you will work in Front and Left viewport back and forth. In Front view, select one vertex in the middle of face (shown in image below with red color), and move them horizontally in Left view based on blueprint. Do this one vertex at a time. Repeat this process until all vertices pulled into their proper position.
2. Image below shows what you get after pulling each vertices to make a 3D face. I think you won't have much trouble if you follow the guidelines in blueprint.
3. Next, add more polygons by Shift drag the edge. Move the vertices to match blueprint.
4. Repeat the process until you get nice head shape. Of cource you will need a little bit of welding and cutting. Tips: Always looking at Top view, the head should be rounded
5. After half of the head is done, select all vertices in the middle. In Edit Geometry rollout click Make Planar X. Position these vertices exactly at the middle of Naruto's face. Jot down coordinate X value in the bottom of the screen. You will need this later.
6. Turn off all sub-object selection. Apply Symmetry modifier. In modifier stack, click plus (+) sign left of Symmetry row. Highlight Mirror. Now, mirror axis is selected, and we need to move its position. Enter the same coordinate X value as you jotted down in previous step. When finished, apply Smooth modifier. Activate Auto Smooth. Actually, applying Smooth is optional right now.
Naruto Modeling Tutorial: Head Part 1 | Part 2 | Part 3 | Part 4