Drawing Head and face is one of the most challenging task of the carton maker.
Here is one tutorial that will give you some guidance and good practice.

   cartoon_head1

Cartoon Head 1

 

 

  

Draw an oval and divide it into in four parts as shown in the example graphic.

Please think of this oval as solid 3d object like egg. If you see as a 2D shape you will have difficulty in drawing the head.
  cartoon_head2

Cartoon Head 2

 

 

 Now draw the eyes on the horizontal line as shown in the example. Note that how close the eyes are to the intersection point of the horizontal and vertical line.

Also draw the eyebrows and see how your the cartoon head is taking shape.
   cartoon_head3

Cartoon Head 3

 

 

 Now it's time to go ahead and add more details to your comic head. In this step you will add nose to your cartoon character. After adding nose again note the area of the face the triangle made by two eyes and nose tip covers.

It is actually a very small part of the entire face. Many new aspirants get this wrong, so be careful.

Add the ears as shown in the figure. Cartoon head 3
   comic_head4

Cartoon Head 4

 

 

 Add mouth now. See how adding two simple line can create sunken cheeks.
Create sunken cheeks on both the sides.
 
   comic_head5

Cartoon Head 5

 

 

 Now it's time to add some hair.
   comic_head6

Cartoon Head 6

 

 Now give finishing touches using shading and shadow technique.

Now start drawing you own comic heads. Use the techniques from this
tutorial's lessons and keep on adding to your bag of techniques by continuously
learning new approach to complete a drawing.

Do not loose heart if your drawing does not look professional. Keep on learning and
practicing soon you creations will not only satisfy the perfectionist within you but also amaze others.
 

Happy cartooning.