Well, you certainly have a style. Your linework's nice and tight, too. For the style you're working with, the proportions are decent, though like Sky and you have pointed out, there seems to be some issues with waists and hands. I would suggest adding some hips, but that would give the characters female hourglass figures. For male characters, widening the waist a bit will help, though.
As for hands... Hands are notoriously difficult to draw. However, remember that every artist has a hand to use as a model. And if you need a specific angle, ask someone to model for you. This also works for drawing difficult poses, too. Studying how your hands are structured when either in a fist, holding something, flexed, etc, will help when drawing them.
Otherwise, the drawings are pretty nice. Don't be afraid to break out a pencil again. The more you draw, the more you'll get the hang of the more difficult aspects.