Although camera angles and lighting do a lot for an image, I think I would emphasize textures and transparencies as making the biggest difference for realism. But (at least in this context) it's always better to show than tell. So I would suggest going to the webring links on the right side of the page, probably the "next 15 entries" link. Check out sites like PoserFactory, Digital Babes, and RENDERoCITY. The stuff (at least at the first 2 I listed) is free to download, use (non-commercially), and study. I believe Kozaburo has a tutorial on transmapping hair at one of the first 2 sites also. The regular P4 nude fem (Posette) doesn't seem to have as many photorealistic textures as Vicky, but there is a Vickybuster texture in the FreeStuff section at this site that might inspire you. Rendering in Bryce might also help; I am no expert in that regard, but I have seen forum threads and tutorials on that topic galore.