There are rules that you're supposed to follow if you want to wear denim-on-denim. I've even written about them; they include things like making sure the denim pieces are different weights and colors, breaking up the look with pops of color, et cetera et cetera.
But honestly? To me, the key to this look is dealing with the fact that you're wearing head-to-toe denim and maybe overdoing it just a bit. Nothing wrong with that.
How I broke up this particular denim-on-denim look: with brown leather accents (and a touch of floral), and - most importantly - a shot of neon. Ooh, those heels.