Another thing I thought of is blurring the background. It will help with the whole depth perception, after all, when talking to someone(I'm assuming you aren't checking out the ass[or the fire, or the fight, or whatever] across the room), you focus on them, and the background will be blurry.
And another thing includes lighting effects. If you think about the light placement and the effects of objects between another object has on light, you can assume that things far away and closer will have different lighting(unless it is like… I don't know what they're called. Those rooms where you can't tell where up is down or etc.).