Re: Help me to achieve extra dark in portrait drawing
Agree with above comments...but if you're insistant on staying with graphite, your 4B should've netted you darker blacks than what I'm seeing.
For instance: The teeth are rendered beautifully, but aren't accented enough by dark tones, so it makes the entire mouth look "flat". Just an example, if you look on the viewers right side of the mouth, the tongue and back tooth should be DARK, but they're not. The mouth creases from the smile has lots of dark, but they're rendered VERY light in comparison. That 4B will do the trick, just don't be afraid to use it more. Also (even though some may say otherwise), if I need a dark line, then dangit I'll push that pencil hard enough to give me the desired tone.
You have FANTASTIC accuracy, the placement of everything looks great...I'd just push that 4b in, blend, 4b, blend....until you mesh it in with everything else.