The outline is defined and worked out, complications (which in this case could be found throughout the drawing) pinpointed, a plan devised.
Being right handed, I've started on the left and worked towards the right in order to not smudge my work.
The paper is an ultra smooth one known as Mellotex, it is brilliant for getting fine detail but allows for no sloppy work or mistakes in the pencil strokes.  It also needs a lot of work to bring up the dark shades.
I've used mainly a 2B graphite with an under layer of 6B for the cats fur.