Just checked your progress in here. I really, really like your sketches. They're so organic, they feel "alive" - this effect somehow fades a little, when you're getting into rendering in some pieces. Probably, you have to push contrast a little bit more, push the shadows to some darker values, to retain the depth of the shapes. There are a few portraits here that nailed it, like the black girl with blue gloves - look how her jevelery pops out in there. You're doing a great job overall. Can't wait for more!