I opened one of the OC areas to see what settings they defined for realistic firelight (torches, candles, fireplaces, etc). Based on that, these are the settings I am using for basic light sources:
Behavior
- Lerp: False
- Flicker: TRUE
- Flicker Variance: 0.05
- Flicker Rate: 18
- Flicker Type: Jumpy
Shadows
- Cast shadow?: True
- Shadow Intensity: Between 0.3 and 0.6 depending on how it looks.
You may also want to nudge the colors just a bit towards red and orange. Not to the point of being overpowering, but just enough that it's not plain white and gives a subtle red/orange undertone.