Our pencils range from 3H to 6B. H stands for "Hardness" and B stands for "Blackness." 3H is the hardest pencil we have and therefore the lightest shade. 6B is the blackest pencil we have and therefore the darkest shade. Be intentional about your choice of pencils to create the full value scale in your portrait.
Remember to think in terms of value! This portrait has six distinct values. Where are your highlights, shadows, and mid-tones?