Original Author: Azuredawn
When: Any time you like, preferably when outnumbered
What: Luring an enemy to a spot, then attacking and killing him.
Why: If you're not the best at head-on combat, this is useful. Especially when you're the last man standing.
How: Distract your enemies in some way, so they come to you. Shoot, so they can see your bullet trail, and go to that area. This is risky though. You might run into them while finding a nice spot from which to ambush them. A better option is to grab some ammo from the ammo cache: it makes a loud noise, and enemies can pinpoint your location, as there is only one ammo cache in most maps(except Crane). Once you made a distraction, find a good spot, with a view of the place you made the distraction. Usually, you would be quite near to your enemy, so aiming isn't a big problem. Beware of multiple enemies heading to the distraction point, though.
Bonus: You can use third-person to peek around corners, so you know which direction the enemy(or enemies) are coming from. Not recommended for first-person though - you have a better chance of being spotted.
How to practice: Stamina management might help if the enemy is near, and you need to hide quickly. Other than that, you'll need to try this over and over again.