for dark circles, i've seen a big improvement by thickening the skin. i've had them my whole life, since grade 4. my mother and sister have them also. they've pretty much ruined my life, but fortunately now i'm winning the battle.
i have been using Collagen Building Serum by
http://www.skinactives.com Skin Actives is the bomb, they sell do it yourself products and pre-made serums...and unlike the stuff you find in stores, they have actual good ingredients.
When I get some money I am going to add a lot more to this than just the serum. Including KGF, retin-A, GHK copper peptides (on days I'm nto using vitamin C derivatives) , coconut endosperm (containing kinetin), ascorbyl palmitate (on days I'm not using copper peptides), oat beta glucan, and I'm sure some other things when I spend some time to really think about it.
Also, very good idea to use lipids to stay in the skin, to decrease translucency.
If the dark circles are from puffiness, use Green Tea Extract with caffeine, it will not only thicken the skin via keratincocyte differentiation, but decrease the water retention w/ the caffine.