i try to catch some likeness and expression to the faces
Love how much of the gesture and feeling you've come across with those faces, great job. Keep it up.
As a result, your edges and outlines are the teensier bit far too itchiest and choppiest to my sensibilities. Would you kindly be able to do 30 minutes of 30 second quick expression preliminary sketches?? (60 ruff sketches) The reason is, as long as you do this kind of approach to improving your line quality and control and consistency, your lines will become the most spontaneous, elegant, and analytical. For more details, be sure to study some faces and expressions with a copy of this pdf here, "Action! Cartooning" by Caldwell
Cheers, and I hope you'll find these helpful, entirely.
The economical use of lines is very effective, by implying almost as much as it states on the paper. the second one is the best in my opinion. Good work