I have found that a grey or silver works best for this simple Black Widow design. I used butter London in Dodgy Barnett. For the webs and spider I used my trusty Stripe Rite in black. I love the brush! Its so fine, yet picks up enough polish. You could also use a fine art brush and black polish for the same outcome. Just remember, less is more when picking up paint onto the brush.
Lets start with the web. Use very light strokes. The thinner the better.