Finally checked out your SB, you draw very nicely and your still-lifes and studies are great! One thing I'm noticing though is a stiffness in your drawings of people. If you haven't tried gesture drawing yet, I recommend it... basically in a 30 or 60-second pose, you draw the model in a quick, fluid motion without lifting your pencil (or charcoal) from the paper. It's important to look mostly at the model and just glance at your drawing every now & then. I usually start with a 'line of action' down the spine but there are other ways that work too. this is a pretty good example of gesture drawing. Once you've warmed up with that, your longer poses will start to look more fluid too.
Good luck, keep up the great work