If you are playing as black, see if White decides to exhcange pawns or play 3. e5. If he plays 3. e5, attack d4 with both knights, eventually bringing your queen to b6. White will not have enough defenders at this point, and he will bring his dark square bishop to aid the defense. With your queen on b6, you can take the b2 pawn for free and still keep pressure on d4. However, White may try to use to his advantage Black's bad light square bishop.