There are some hacks in using HDRIs to illuminate a scene, but they are easy to use.  Ambient occlusion will enhance shadows and improve a scene, if used properly.  The biggest issue I have found in applying AO to La Femme and L'Homme figures is the eyebrow material zone.  Its relative proximity to the face creates very heavy shadows when applying the AO node with a high distance value.  Dropping that value to a distance of 0.001 negates the shadow affect, so ATM, there isn't a solution yet for its application.  An AO map might be the solution, but you will need to create it independtly with a 3rd party program or online service.