my personal favorite way to conceal dark circles (of which i have much, permanently, it seems) is to use a light concealer (usually one to two shades lighter than one i would use as an actual concealer to conceal imperfections, but matching my undertone) as a cream highlighter. i use a triangle shape underneath my eyes, down the length of my nose and then arching back upwards to the corner of my eye. i blend it upwards toward my eye with a damp beauty blender and then usually set it with translucent powder or a banana yellow powder so it won't crease. this makes my face look like it's illuminated and i received the actual eight hours of sleep that i had.
you can also color-correct if yours is bad -- a salmon powder will work vs. the yellow, & i've heard of tapping a light, light layer of red lipstick to cancel out the blue of dark circles before applying foundation can work wonders.
here is a picture of my face showing and i've outlined in pink to sort of show where you can see the general shape of where i put the concealer before i blend it out. without the concealer, i have very large, dark circles that are genetic from my mom :|
as for product recommendations -- i personally use a variety because i'm a make-up junkie: for high-end, nars creamy concealer is considered one of the best, and i'm a fan of the urban decay weightless complete coverage concealer too. HOWEVER, those are quite pricy! so for drugstore, maybelline instant age rewind is AMAZING -- creamy, though definitely on the lighter side of coverage -- and the nyx HD concealer is a decent dupe of the nars. for the setting powder, i use the banana powder in my anastasia contour kit or kat von d kit, but my ultimate favorite setting powder is actually this one. it smells super strong floral, but it is cheap and finely-milled and you get SO MUCH for the price when you really only use a dusting. i use it all over my face to set my cream products before contouring and i get no "settling into cracks" (creasing) when that used to be an issue for me too.