Probably the easiest ones to color were the black and white "tuxedo" cats. For all of the cats, I mostly used my pastel chalks. The ones I have are a set of 48 from "The Stencil Collection". I love that they are erasable when you first apply them, but set within 10 minutes or so. And I like the ease of use.
For this black and white cat, I started by stamping a black image on white card stock. Using the chalks, I started by coloring the nose & inside of the ears with pink. Then I added a dark grey - almost black color around the face and body, leaving plenty of white showing as you can see. I then added black chalk where the lines were on the cat and other places I wanted to be a bit darker (like where one part of the cat would create shadow on another part).
For the eyes, I combined 2 Smooch inks (Green Apple, & Gold Lame') by putting a few dots of the green and then blending with the gold. I used a bit of pink Smooch ink for the nose.
I found it looked best if I then went over the lines with a fine-line black felt-tip marker. (Sharpie's works fine for this.) The head, body & bow are just sitting loosely at the moment, but I had to see what they looked like. Won't this make a fine addition to a card?
Here are a couple more black & white cats.