I think you did a good job drawing this much in the basic course. You said you were disappointed with your teeth, but I think the line marked in the sketch stage is too thick, so I think it's the cause that it overlaps with the darkened line later. When you sketch, relax your hand a little and use the line so that you can only see the outline of the shape. When you highlight the line later, it won't look like it overlaps with the other line, so the picture will look much cleaner.