Standing out in the open is a surefire way to get yourself killed in Modern Warfare 2. Anything that stops bullets will work as cover, as long as you’re standing behind it. There’s no danage bonus for taking cover. If you take a bullet while hiding behind a rock, you still take the same amount of damage. The idea is that if you’re doing it right, you’ll simply take less bullets.
Always, always, always take cover when reloading. There is absolutely no reason that you should ever be out in the open while reloading your weapon. This is the definition of a sitting duck.
It’s also important to quickly move from one cover to another, even if you’re just going back and forth between the same two locations. Switching cover will trip enemies up for a moment, buying you valuable time to get shots in.
Like seemingly all videogames nowadays, Modern Warfare 2 features regenerating health. So when you start to take damage (you can tell by the screen turning red), take cover and let yourself heal. This may be time consuming, but don’t get impatient. You don’t want to die like an idiot. On veteran, you’ll be hiding and healing a lot, so firefights can often take a long time.
High caliber weapons can shoot through flimsy cover. This means that if you’re packing some serious heat and the enemy is hiding behind a flimsy wooden crate, you can just blast right through that cover. This also means that if the situation is reversed and you’re the one hiding behind weak cover, you could be in trouble. Look for something visibly solid, like a tree or a concrete wall. Wooden cover is rarely a good idea. There are no hard and fast rules about what is good cover and what isn’t, so just use common sense.
If you’re surrounded by enemies, always put the cover between you and the largest group of guys. This way you can stop worrying about them and pick off anybody trying to flank you. The enemies in front of you should always be your very last priority, since they can’t hit you anyways!
Article from Gamersyndrome.com