I’ve read many times that you should be facing where the enemy is before aiming down the sight in first person shooters. If the single player campaign in Bad Company 2 or Modern Warfare 2 is good for anything it’s for practicing this. Disable aim assist and face your enemy before bringing the sights up. You’ll aim and kill faster. Once you get used to it anyway, as I’m still learning.
Leading on from this is the obvious advice that you need to know where your enemy will be in any situation.
This of course only applies to medium to long distance shots. Close up you should just fire from the hip as the target is so much larger. You still need to make sure the enemy is in the centre of the screen though!
It is of course much harder in multiplayer games. The NPCs in the campaign obligingly stand around shooting but not mortally wounding you as you take sight.
One incident where this would have been useful was on Arica Harbour the other night. I was running between two cargo crates and I wasn’t facing dead straight down the passage. A guy came around the corner, stood in the middle, and I was facing slightly to his left. In a fright I jammed on the fire button but round after round went thudding into the sand by his feet and he calmly dispatched me with one round.
Also worth considering is Geoff‘s technique of firing off a burst before you aim down sights, you’ll probably get a round or two in and then finish them off when they’re hurt and disorientated. Must dig up one of his videos where he demonstrates this.
I admit my aim mostly sucks in first person shooters, so take what you read above with a grain of salt and go look for better advice elsewhere. 🙂