How to draw a portrait at the grey pencil
We are going to see the creation of a portrait at the grey pencil, stage by stage.
The first stage is crucial in creating a portrait. You must get the proportions right: the positioning of the elements that enable the person drawn to be recognised. Put in references if necessary. Measure and compare, but before entering the details, sketch the shape of the face, nose and eyes, etc., to be sure of getting close to those of the model. It's better to start working with a light pencil.
Then start to look at the correctness of the lines. Of course, adjustments may be made to the positioning of the eyes and mouth, etc. at this as at all stages.
Gently start to shape the face, always with the same pencil.
Take a broader pencil (2b for example) and start to put in the values.
To finish, take a fairly broad pencil such as 6b and draw in some contrast. This will give volume and life to your portrait.
Bear in mind that this is quite a school-book method to create a portrait. Don't hesitate to try out other ways and other depictions. A portrait isn't a matter of values and proportions: producing a portrait is above all a question of sensitivity.