For realistic lighting, I can't recommend highly enough Richabri's Light of Day set (http://market.renderosity.com/softgood.ez?ViewSoftgood=28046). I use these for nearly all my renders, though I tend to add a Front (infinite) Light at 0,0,0, and then move as needed so that no matter what angle I'm "shooting" at, that light is always front and center to "fill." Of course you don't always want that portrait style lighting, but with the LOD set, you can achieve almost any style lighting, indoors or out,by fiddling with the colors. Only one light, the Main light, casts a shadow, and this also can be changed as desired. THe point is, Rich's set gives you a nice configuration to start from. I have a LOT of the RTDNA free sets, as well as sets from DAZ and elsewhere, and I've yet to use them. And as Demonshane said, go for quality above all. Lighting will make or break a render.