Firstly, I'm gonna give you some tips on how to draw heads. In my opinion, the shape of the head would depend on the gender. But starting the heads are very similar for both genders. 

First you would start with a simple circle or oval. The the shape of your choice does not have to be perfect, it just has to be round. Then after you draw your preferred shape via a circle or an oval,  you  can then draw a cross shape in the middle of your shape. The cross shape helps you map out your face easier. 

After you draw the cross shape,  draw the jaw line ( you can use both tips for both genders). For a male you draw a square starting from the middle of the cross to the bottom of your cross.  For female  you flower petal like shape starting from the middle of the cross to the bottom of the cross. The flower petal shape does not have to be pointy. Draw your ears. Then finish drawing the rest of the head. (Remember that the neck is attached to the back of the head for side and back view, for front view, just draw two parallel lines under the chin).

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