Darken the negative shapes and add details to finish
Darken up the negative shapes in the background so that they help pull the highlighted areas of the arm of the chair, giving depth to the drawing. Then darken any of the shadow areas you feel might need more depth, like behind the dog’s head to separate the head from the cast shadow on the arm of the chair. Use very sharp 4B and 6B pencils for those rich darks. Sometimes a 4B will add that richness the drawing needs and really push the contrast in a piece.
Since the hair on this dog is medium length, your pencil lines should match the length of the hair and go in the direction of the fur. With a very sharp 2H pencil, work from the dark areas into the lighter areas, creating negative spaces between the strands of lighter fur. Then use an HB pencil to darken them up as needed.
The black of the dog’s nose with the white fur around it is a high contrast area, so you don’t want to create a harsh line between the two. You want a nice gradual shift between the very dark nose and the white fur. Layer in 2B pencil and then 4B pencil over that. Tighten up your crosshatching at this point. The back-and-forth motion of the pencil should be only around ⅛”. Darken up the nostril with a very sharp 4B pencil.