You may want to keep some paper beside you as you smooth tone to make sure your pencil point is not too dull or sharp. This video shows how I do this.
Finishing and Perfecting
After going back over this section with an HB pencil, it looks smoother than it did before. This is one of the ways you finish your drawing.
At this point in the drawing stage, clean up your drawing by erasing smudge marks, sharpening lines, and making sure that even the smallest details are accurate. Be nit picky!
Now you can take a step back and observe your work. (Do not forget to sign your art--this is important!)