up your sensitivity little by little I think you start off around 35 I currently have mine set to 80, it's really good for spinning around when being shot in the back etc.
For most games I would agree with this, however, I have found in Crysis 2 it is much easier to have a sensitivity around 15. Sounds crazy, but I am WAY more accurate and can get head shots better. When the sensitivity was too high I kept spraying everywhere and had a low accuracy. You do forfeit some maneuverability but I think its worth it.