Watch this: http://www.chess.com/blog/Walter_von_Entferndt/caro-kann-2-knights-variation-a-gentle-introduction-by-gm-baadur-jobava
I prefer against the Two-Nights Variation 3...Bg4 because it is holding the pressure on e4.
Watch this: http://www.chess.com/blog/Walter_von_Entferndt/caro-kann-2-knights-variation-a-gentle-introduction-by-gm-baadur-jobava