I had a k/d ratio of around 0.95 for a very long time until I bought a pair of Turtle Beach headphones (google it) and i'm now up at the 1.75 mark.
Once you have the headphones set up, you need to adjust the 'game' sound options to dull down the music/cinematics etc and pump up the SFX.
Not only can you hear footsteps etc a lot clearer you can actually hear which direction the sound is coming from... An obvious advantage for modes like Hardcore S&

!
(I bought the Turtle Beach PX1 headset for PS3 for £65 inc p&p.. maybe a little expensive for most people but worth it if you're a serious player or give a toss about your stats)
Check out limexb360.com for some good deals