For clarity, @Nighto is referring to our COD4MW2 server. Nighto has a different game style than the majority, which is run & gun. He's right about the accuracy, if you make an anticipatory shot in front of the player you are most likely to get a kill as opposed to shooting right at the player. I have often gotten kills which I didn't think I would, people disappeared around the corner and I shot behind them, but my bullets seemed to have made a turn and chased the opposing player to kill them.
The one thing that helps a fair bit is using /cl_packetdup 5 I only recommend it for players with really high ping, 120ms+. So, the fuckers with 18ms ping, fuck you, dont use it, seriously fuck your ping, I am jealous.