Also you can bring the ranges of your lights down and make sure you are not using full bright colors for you lights. Bring the Lumination down to 100 or so to have better low lighting for darker scenes.
This of course is after you set your ambient setting to what you desire.
Which shaders are you using? Vanilla or some of the bond1 ones?
Maybe post a screen shot or two to let us see what you are seeing.
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