American model Martha Hunt, after Alexandre Vauthier, Paris, July 2013.
For a cute, casual summer look, layer a denim shirt over a tank or tee and team with a leather mini + ballet flats. 
Recreate Martha's look (kind of):
Topshop Moto denim oversized shirt,  ASOS Denim shirt, Paige Denim Kadie button up shirt, 7 For All Mankind denim shirt or Acne Wave denim shirt
A.L.C. Reese leather skirt, Vince leather skirt, Rag & Bone Louise skirt, Oasis faux leather skater skirt, or Townsen faux leather skirt
Rag & Bone Louise ballet flats, Marc by Marc Jacobs studded mouse ballet flats, ASOS Laila ballet flats, Repetto ballet flats, or Lanvin ballet flats