Portrait portions are general guidelines, since all people are different things change as the person does. Most people are pretty close to these though! Look in a mirror or at a picture of yourself to help you with your self-portrait. Check out all the SYMMETRY our faces have.
Change the shape to match your own face
The face is five eyes wide
Are you smiling? Can you see your teeth? Here is a link to a tutorial for how to draw a smiling mouth... https://www.youtube.com/watch?v=Y_H6fj4C738
What does your hairline look like?
What does your shirt line look like?
Have fun! Can't wait to see your portraits... check out the tutorials if you need help drawing certain features.