Making a human bust is probably the most intimidating project I ever faced. I have now made several, and each time, my stomach flops in anticipation. How will it turn out? Will I do a good job? Will it look terrible?
Think about the following points as you plan your sculpture:

• Measure the face and the placement of the features.
• Start by making the skull, not including the hair. Add the hair on later, as a solid piece or pieces.
• Draw on the skull where you will place the features. 
• Make both eyes at the same time, so that they are the same size and evenly placed.
• Watch videos on how to make lips, a nose, the brow, the eyes.
• Don't be afraid to cut off, cut back or redo any portion of the face. Practice makes it better!
• Add accessories, like hair, glasses, clothes or jewelry last.

Your bust will be about 7" tall, including a 4" skull and the neck and shoulders. It will be hollow. I suggest starting with a pinch pot to make the front of the face, and then adding on the back of the skull as a shallow pinch pot.
The neck will be a coil, and the bust will be another shallow pinch pot. Make a vent hole though the bottom of the sculpture into the skull so that you do not have an enclosed form.