I usually start with the good old circle method and mark on the outlines with a cross both ways, whilst marking the ear placement. Then I follow the guidelines of the rough sketch as close as possible, while making adjustments along the way to look better. 

 My personal tip for drawing faces is by first marking out the placement of the eyes, since it is usually the focal point of focus on an art piece. So I draw the eyes first majority of the time, and also including the drawing I've submitted. This ensures that the face at least has some balance. Therefore when I'm confused on how to start a face drawing I focus on the eyes placement as a guide.  #XPPenTutorialPractice.