Lighting effects -- some white soft brushing around where the render is, either set to soft light or lighten with lowered opacity, usually works for me
Render effects -- you just have to mess around with those. Try duplicating the render, desaturating it and setting the desat layer on soft light or overlay. Or duplicate, gaussian blur (at 2.0) that layer and set it to soft light. Or even combine the two. It really is, though, about just experimenting.
i do what Baggs does when it comes to render effects.
duplicate layer and desaturate, and set the top layer on overlay or soft light
lighting effects: blur a lighting stock to the point where its just a blob, but make sure there's some grey/black/white. dont blur it all the way is what i'm saying
it could be colored which gives some nice lighting, but desaturated looks good as well