Problem
I want to cut this model out from the background, the issues with this image are:

 The hair which is very spikey and translucent in places

 Places where foreground and background colours are very similar such as around the chest

 Color blending issues around the nose

Solution
I didn't adjust any of the IIL settings for this one. I started this image by masking the background which was fairly easy. There were some issues around the chest and neck with mask slipping over the edge. So I used the force edge tool.

I found very useful:

 the preview camera to get just the right bend at the edge. I found that there needed to be a bit of noise to make the image more authentic

 Smooth for difficult edges where the mask was a bit bumpy at the edges where there was some spectral effects

I then used "Auto-Fill" with Auto-Complex on medium which took care of most the image. Next came the hair, the problem here was that my selections hadn't picked up patches of background hiding inside the main body of the hair. To get round this I sectioned off the hair with the Regional Tool and erased keep mask inside the region.

Then I painted complex mask over the unmasked area using the exact tool - I made sure it didn't affect the existing delete mask by checking the box. This left the complex covering any particularly wispy bits of hair and any background which previously I'd missed. Then using small dabs of local keep mask on particularly solid bits of hair I painted in much of the solid hair - but missing the translucent bits. I used the preview tool as I went to ensure the accuracy of the mask. The hair looked great. It took around 15-20 minutes to complete.